The BONUS BALTSPACE project explored MSP integration challengesand identified the following challenges and limitations under three major themes including:

1. Multi-scale and transboundary integration

• Integration between different (geo)political scales (e.g. local, regional, national, international) 
• Integration of MSP across national borders
• Integration of MSP and terrestrial planning 

2. Policy and sector integration 

• Integration of environmental policies (in particular MSFD) and Blue Growth 
• Sectoral integration in public policy (e.g. maritime transports, fisheries, tourism etc.) 
• Integration of public, private and voluntary sector activities Stakeholder integration 
• Integration of stakeholder knowledge, values, interests, critique etc. in MSP with regard to important procedural aspects (e.g. transparency, legitimacy, power, mobilisation, timing, roles) 

3. Integration of knowledge base 

• Interdisciplinary integration linked to e.g. risk and uncertainty analysis, sustainability assessments
• Integration of sectoral knowledge 
• Integration of decision support tools in practical MSP processes handling ecological, economic and social issues on a spatial level

The BALTSPACE interactive tool facilitates exploration of these challenges and their related aspects.

Cross-sector integration implies good knowledge of the implication, requirements and planning criteria for collocation of sea uses. In particular it is important to analyse costs and benefits of different combination of uses in different circumstances (e.g. legal, oceanographic, economic etc.). There are several tools and guidelines assisting planners in this process. E.g. Individual Stress Level Analysis - ISLA quantifies the impact of future activities on the specific activity, E.g. it allows to estimate the effects of future management on fisheries based on the closure of fishing grounds. BONUS BALTSPACE project has elaborated guidance on how to use a tool to analyse the distribution of costs and benefits associated with a given set of maritime uses.

Also more comprehensive approaches do exist. The Latvian pilot plan provides a separate "Cost-benefit analysis for balancing sea use interests within the LV MSP process". The Seanergy 2020 project developed the study  “Cross-border MSP Case Study Benefits Assessment”; this shows how to evaluate the benefits of cross-border coordination of MSP, focusing in particular on offshore wind energy. Finally, Marine Planning: socio-economic study might help maritime planners, developers, local authorities and others to understand issues affecting coastal communities. It includes national level information and more detailed information for the East of England, also regarding parallel uses of the marine area and associated costs and benefits.

The MUSES project has elaborated: (i) a comprehensive overview of opportunities (analysing related benefits) for multi-uses in given sea-basins; (ii) analysed perceived and real barriers to various forms of co-uses across all sea basins, (iii) defined a multi-level action plan recommending priority issues to be tackled to overcome those barriers and exploit such opportunities.

However, while looking for inspiration it is important to keep in mind that the “one size approach fits all” should be avoided. In each case costs and benefits might look different. They depend of the level of development of a given area, stakeholder consciousness and even planning culture and experience. Thus, they are context dependent.

MSP aims for win-win solutions. However, this is possible in exceptional cases only. More frequently spatial conflicts prevail. Different sea users compete for the same sea space. For instance, fishing can be hampered by any solid construction in the sea but also by the same token by an intensive navigation, underwater cultural heritage or underwater pipelines and cables. However, the same uses can bring also synergetic effects since underwater constructions with time might become artificial reefs: an important place for fishes to shelter. Therefore it is so important to analyse possible spatial conflicts and discuss trade-offs that might require political decisions as a part of the MSP process. The departure point is usually the mapping of sea uses, facilitating visualization of possible conflicts (and synergies).

The COEXIST project offers a good example of a tool for mapping of activities - past, present, and future. The dedicated GIS software helps to analyse and visualise information on the location of the current and planned activities. It addresses the following questions: ‘Do overlapping activities exist?’, ‘Where to expect conflicts?’ and ‘How does a specific management result in a change of conflicts?’. Geo reference Interactions Database – GRID elaborated under the same project is a web-based flexible database connected with a number of tools (stress level and conflict score analyses) to review marine activities and interactions (conflicts and synergies). Whereas the Web-GIS platform for implementing MSP in Greece and Cyprus might be helpful for visualising conflicting interactions (considering both maritime and land-based activities and uses) and deriving density activity maps and/or conflicts maps. There are also several tools that might help quantifying the overlapping uses and calculate conflicts scores and other indicators (e.g. including costs). One example, among many, is the Analysis of Conflict Scores tool developed by the COEXIST project, which supports a (semi-) quantitative conflict analysis and can answer some questions such as how does the conflict score change with management options or did a changed management result in a change of conflicts. The conflict score tool, developed by the Adriplan project, is based on the above. It allows to quantify the overlapping of uses, calculating the direct spatial conflict score (in the current and future scenarios) based on the COEXIST methodology. The method includes five consecutive steps: (i) identification of maritime uses; (ii) spatial normalization of uses on hexagonal grid; (iii) setting of temporal and spatial attributes for each maritime use; (iv) calculation of the co-existence score per each pair of maritime uses insisting in the same cell of analysis; (v) calculation of the total coexistence score per each cell of analysis.

Individual Stress Level Analysis - ISLA also developed by the COEXIST project, quantifies the effects of future management options on concrete sea uses. Many pilot projects have also used the MARXAN software for planning new uses in a way that allows minimising spatial conflicts while achieving the agreed policy goals (e.g. on nature conservation, off-shore energy production or fishery). Results are available in the BaltSeaPlan project reports no.

Maritime ecosystem forms a unique continuum hardly affected by administrative borders. Exploitations of some ecosystem services in one country and resulting from these negative externalities may affect societal wellbeing and the state of the sea environment in other countries. The influence varies. Oils spills might travel quite a long distance, solid construction might change the transfer of sediments and thus affects coastal dynamics far away from the place of its location whereas laying of pipelines might hamper international navigation and affect ships from outside of a given sea basin. Therefore, some conflicts would benefit from a formal dispute resolution. Its preparation is not an easy task.

For instance in the Baltic Sea region the BaltSpaceVISION 2030 endorsed by VASAB and HELCOM identified four topics required more intensive trans-boundary collaboration: offshore energy, fishery, nature conservation and navigation. Thus, some Baltic Sea region countries several times have raised the questions of the need to establish some kind of a formal macro-regional agreement regulating those topics. Some preparatory work has been started under the international projects such as BalticLINES and BalticGrid. It is however, not clear whether they will results in some kind of a formal agreement or guidelines (good example of such recommendations is provided by Seanergy 2020 project).

Another form of formal resolution of international spatial conflicts is making use of existing international treaties and convention. For instance, Norway has managed to reroute the international navigation potentially jeopardizing the environmental integrity of its coastal waters through the International Maritime Organisation (IMO) framework. However, there are also some good examples of bi-lateral and multi-lateral formal agreements of different nature and scale that help resolving some spatial conflicts. On a local scale one can study and follow the case of Wismar Bay. Through an intensive stakeholder process facilitated within the MSP framework tourism sector convinced the German nature protection authorities to allow the usage of the environmentally sensitive waters in the certain period of time. Sea tourists (mainly boat owners) subscribed themselves under the ban of not entering those sea areas in the time in which they are closed. At a larger national scale one can study the UK experience in preparing different types of agreements.  In UK wind developers and/or submarine cable companies and fishery industry representatives develop written agreements, such as Co-existence Plans (agreed-upon communication protocols; measures for avoidance, mitigation, and cooperation; and dispute resolution), Memoranda of Understanding (MOU; articulate goals for engaging with fishermen, for example, on routing cables in nonessential Fishery areas), and Statements of Common Ground (summarize discussions on areas of agreement and remaining/unresolved conflicts). Each form of conflicts resolution shows particular strength in different circumstances. For instance, the Co-existence Plans are mainly linked to the offshore wind, WOC (World Ocean Council) or grid-nets while Memoranda of Understanding work well with regard to routing cables in non-essential Fishery areas with consent from fishermen.

The study titled Addressing conflicting spatial demands in MSP: Considerations for MSP planners was conducted in 2018 with an aim to explore the range of spatial conflicts experienced in MSP in Europe. It provided an overview of common types of spatial conflicts and solutions that have been found in various EU Member States, with particular focus on spatial conflict prevention and mitigation and conditions for applying them.Detailed results of the study and relevant examples are presented in nine conflict fiches available here.

Cross sectoral synergies can be achieved in practice and at the operational level through the combination of different maritime uses at the same location or with multi-use offshore platforms which contributes to the  sustainable and efficient use of maritime space and natural resources. Combining uses, both in close proximity, through joint operations, or on the same platform, can reduce space demand and potentially offer significant socio-economic and environmental benefits. The concept of multi-use is still relatively new and has been mostly advanced by research institutes/commercial enterprises which is also the participants involved in the stakeholder analysis.

Multi-use in Europe has so far been explored at the project level. The TROPOS project designed a modular MU platform concept for use in deep waters, focusing on the Mediterranean, tropical and sub-tropical regions. The MERMAID project examined different design concepts, such as the combination of structures or different uses at representative sites under different conditions. H2Ocean instead focused specifically on the combination of wind and wave power for hydrogen generation, supporting multiple energy users. The MARIBE project focused on analysing and developing business cases for a selection of most promising MU combinations. 

The MUSES project went beyond exploring technological solutions to review and analysed other barriers and opportunities for a variety of multi-use combinations at the national and sea basin level. The following project outputs give examples of multiuse opportunities in Europe: 

• The MUSES project Multi-Use Analysis report provides a clear overview of multi-use potential (including environmental, economic and societal benefits) and barriers specifically  for 13 multi-use combinations.
• The Sea Basin Synthesis report identifies potential and barriers for MU applications across the five European sea basins, depicting MU applications with real potential and maps out their location and the opportunities to promote MU implementation. 
• The MUSES Multi-Use Action Plan builds up on all the MUSES work packages and reports to provide actions and recommendations on what should be done, and by whom to address multi use barriers.

These reports overall highlight major barriers (inappropriate regulations, operational, environmental, health and safety, technology, societal and legal aspects) stalling the transition of multi-use of ocean from a concept to real life recognition and practical implementation. They also highlight good practices, case studies and recommendations across the EU related to multi-use concepts. The following are some findings and examples of multi-use opportunities based on the project outputs: 

• The North Sea, Eastern Atlantic and the Baltic Sea have a strong offshore wind energy sector that could potentially develop further while also allowing growth in other relevant Blue Growth sectors such as tourism, fishing and aquaculture.
• Combination of offshore wind, wave and tide energy generation (usually as part of the same physical platform), with the purpose of maximal energy generation from the resources at the given sea space, is something that developers are increasingly considering. For example, there is already some experience in combination of wave and tide energy in the Northern part of Scotland (Pentland Firth and Orkney waters), while a pilot test hybrid wind and wave technology is supposed to be commissioned (Cathness).
• Different approaches can be noticed across countries in regard to integration of fisheries within offshore wind farms. On the other hand, in some countries, new tourism activities have already been established in relation to the OWF (i.e. renewable energy museums and visitor centres, boat tours, etc.).
• Tourism combined with other activities including UCH (e.g. diving and walking trails) have strong potential in the Mediterranean and Baltic Sea and other environmental/conservation benefits of this MU have been realised; and offshore wind (e.g. boat tours for OWF sightseeing), provides additional and innovative tourism opportunities that could potentially sustain tourism sector all year round. 
• The MU combinations that concern the diversification of tourism and fishing sector in combination with sustainability and environmental protection goals are relevant in the Mediterranean, the Black Sea and the coastal areas of the Eastern Atlantic; with existing examples in Italy, France, Spain, Portugal and Greece
• In ‘remote’ areas in Eastern Atlantic with little access to grid, combining aquaculture with wave energy generation (Mingary Bay, Scotland, UK) is driven by the need to use generated energy directly for the purpose of aquaculture operations.
• The North Sea and specific areas of the Mediterranean Sea (Northern Adriatic in particular) have the potential for development of innovative solutions for sustainable reuse of decommissioned O&G platforms