Maritime entitlements are generated by naturally formed land. Coastal features must satisfy certain conditions to generate, and continuously support, claims to maritime zones. They only generate exclusive economic zones or continental shelves if they are above water at high-tide and sustain human habitation or economic life. States establish baselines along coastlines. Outer limits to maritime zones are generally measured from baselines, with the exception of continental shelf limits where the natural prolongation of the continental margin extends beyond 200 nm. These outer limits can be permanently described but all other unilateral limits fluctuate with changing coastlines, in accordance with the theory of ambulatory baselines. States are obligated to adjust unilateral limits and bring them in conformity with the law of the sea. Proposals have been put forth for the freezing of all maritime limits to mitigate the inequitable effects of climate change for particularly vulnerable States. This would involve changing existing rules or at least their interpretation. Changes through subsequent practice are the most viable option but State practice is not yet uniform.