The top on a traditional square rigged ship is the platform at the upper end of each (lower) mast. This is not the masthead "crow's nest" of the popular imagination – above the mainmast is the main-topmast, main-topgallant-mast and main-royal-mast, so that the top is actually about 1/4 to 1/3 of the way up the mast as a whole.