The archipelagos in Aland, South-West Finland and in the Swedish coast are unique environments which have immeasurable cultural, social, ecological and economical values. The sources of livelihood as well as quality of life in the archipelagos are largely dependent on the purity of the nature and thus a large oil spill could be destructive for both nature and people. Despite general shallowness of the archipelagos, oil tankers loaded with more than 100000 tons of oil can traverse them through certain routes. Circumstances for oil combating in the archipelago environment are very different from those in the open sea. In archipelagos the oil will immediately reach countless sensitive beaches and shallow bays that are difficult to access by large boats and often difficult or even impossible to clean. In the archipelagos the limit between the open sea and the shore is not clear which makes it difficult to define responsibilities of different authorities in the oil spill response. The ARCHOIL project aims at reducing negative environmental and socio-economical impacts of an oil spill accident through supporting regional rescue services in developing shoreline cross-border response on a concrete operative level. This is done through two different approaches. The first approach is to develop strategic oil spill response action plans in the archipelagos, where local conditions are taken into account, challenges are identified and functional and efficient strategies for oil spill response are proposed. The action plans will also include plans for immediate protection of selected sites in each region through fixed anchoring points for oil combating equipment. The second approach of the project for increasing preparedness for oil spill response is to increase the know-how of municipal officials and organizations in oil spill response. The length of the shoreline is multifold compared to areas where the continent directly meets the open sea and the personnel of the rescue services will be able to carry out only a fraction of needed operations. Thus it is essential that municipal actors can effectively participate in protecting and informing citizens as well as in cleaning of oiled beaches in their own areas. Cross-border added value in ARCHOIL project is obtained by working together to transfer best practices of oil spill response and join forces for developing oil response action plans and training packages for oil spill response in archipelagos. If a major oil spill happens in one of the archipelago regions it will be extremely important to rapidly get help from the other regions. The readiness to co-operate and share expertise in case of an oil spill will be increased through this project. Achievements: The ARCHOIL project aimed to reduce the negative environmental and socio-economic impacts of a potential oil spill accident through supporting regional rescue services in developing shoreline cross-border response on a concrete operative level. The project developed strategic oil spill response action plans in the archipelagos, in which local conditions are taken into account, challenges are identified and functional and efficient strategies for oil spill response are proposed. The action plans also included plans for immediate protection of selected sites in each region through fixed anchoring points for oil combating equipment. The project also increased the expertise of municipal officials and organisations involved in oil spill response.