Most of the ledges you grab on to will be brown and boring and, well, just there for your top escape the rising tide, but there's a couple of interesting ones. The ones which spin in place can, of course, be used to help you climb faster, but there are also coloured ledges which make different things happen. Green ledges will actually shoot you up the level, allowing you to skip a bunch of ledges. Blue ledges, meanwhile, will actually make hidden ledges appear, revealing the path forward, making them pretty essential.