This chapter discusses the application of the law of the sea in the territorial waters of the Aland Islands and the Aland Strait in light of the 1921 Convention on the Non-Fortification and Neutralization of the Aland Islands. It describes that technical as it may seem in nature, carries evidence of the importance that has been attached over time to thorough legal reasoning in the interpretation of the multiple relevant rules. The chapter presents the tools used in the law of the sea: legal rights, maritime zones, and navigational rights affecting the sea around the Aland Islands. With reference to navigational rights, the most important limitations to a coastal state's sovereignty relate to the right of innocent passage through the territorial sea. Finland did not make any reservations to the 1958 Convention on the Territorial Sea and the Contiguous Zone in terms of demilitarization or neutralization.