Ernst Thälmann Island or Ernst Thälmann Cay is a 15 km (9.3 mi) long and 500 m (1,600 ft) wide island in the Gulf of Cazones. In the 1970s, Cuba promised to donate an island in its archipelago to East Germany, and subsequently renamed what was then known as Cayo Blanco del Sur after German communist Ernst Thälmann. Because the island was not mentioned in later documents incorporating East Germany into reunified Germany, various parties have argued that it remains a territory of the defunct nation, but Cuba has rejected this argument and claims jurisdiction over it.