
Sure is dark in here.

Ecco doesn't know what he is getting into...
Sea of Darkness is a peculiar level in Ecco: The Tides of Time. Unlike many other levels, it is extremely dark and only Ecco's sonar will light it up for a short moment. Your objective is to save that Baby Orca in this area.
Description[]
The Sea of Darkness is filled to the brim with fish and Vortex Drones. It is practically a gigantic dark maze to get through, your sonar is the only way to light this dark location up for about two seconds.

Ecco lit up Sea of Darkness with a sonar a second before this image was taken.
At some point, you will come across an Orca. This Orca lost her child in the Sea of Darkness and also saw the Vortex Queen killing the Asterite. This must explain why the cutscene shown by the Asterite has a little Orca swimming up to see everything in the bottom right.
There will be some Stone Eating Stars nearby in a hard-to-access tunnel. You will have to push them all the way to the end, and then push it up to find a trapped Baby Orca. Save it and return to the mother Orca. You will then be able to get out of this dark maze.
Trivia[]
- Interestingly, it shares the same theme that City of Forever has. These two both have a similar mood: Unpredictable and unnerving.