The name speaks for itself.
The only normal way that the developers left us
Of the things you need: energy cells, food / water, repair tool, reinforced diver suit, flippers, glider (specifically the last two are needed for, to fade if something goes wrong.)
1.When you see a leviathan, cling to it and start drilling it.
2.When the crab has little strength and when the leviathan sailed away, make a crab.
3.Basically, that's all you need to know..
Risky and Long Way
Of the things you need: repair tool, food / water, energy cells, glider, flippers, reinforced diver suit.
1. ram the leviathan
2. make a sailor when the leviathan sailed away
3. The method is quite risky, I do not recommend him, but you can use.