That civilization could have invested in rail transit and tunneling instead. Positioning isn’t so hard on fixed roads, although fixing the, in the first place under oceans could be a problem. They might figure out triangulation using their planet’s magnetic field or something. It’s also completely possible that life isn’t viable at all on non-Earth like planets.
Remember that the gravity is higher. Your mountains are more dense and your oceans have more pressure. You're not living on a world with 14psi. You're not living in a world with the same ground, air, or ocean composition. All these change. So all your drills have to be thicker and harder. All your cables need to be stronger.
