You move on! Speeding along through open water is faster going, but eventually it comes time for you to dive into the tunnels again. It gets darker and darker as you move into the planet's core, until your only light source comes from the headlamps on your submergible.
Oh, as well as the flora and fauna of Naboo's deep sea. The fish glimmer with a natural light at this depth, as do some seaweeds. You pass vents in the crust, where water boils from the core's heat.
A series of decent Pilot rolls means you come through this segment taking minimal damage, as the submarine strains from the pressure. You take 5 damage; not bad, considering what could have happened were you not a capable pilot.
King Evand and Trozen are mesmerized by the scenery; they have never been somewhere like this before. Halloy is decidedly dry.
It is when you are coming near your destination that you start to feel endangered again.