The term 'CASTAWAY's site' can be solved by three different crossword solutions: ATOLL (5 letters), ISLET (5 letters), and ISLE (4 letters). An ATOLL is a ring-shaped coral reef, island, or chain of islands formed of coral. It typically encircles a lagoon and is found in tropical oceans. An ISLET is a small island, usually one that is uninhabited. Lastly, an ISLE is another word for an island, which is a landmass surrounded by water. All three of these solutions could be suitable sites for a CASTAWAY.