The next parts I vaguely remember: swim _very_ slow past an octopus arms (there's a hint but it's not necessarily clear that you have to be barely moving at all), hit key crystals and then the corresponding ~door crystals, and push a rock to drop and follow after them to avoid getting pushed back by the current.
It's generally a series of puzzles of that form and there's some ~light combat stuff.
It's generally a series of puzzles of that form and there's some ~light combat stuff.