Strategy Guide: Ecco the Dolphin - Caverns of Hope
Objectives: Escorting the Rebel Leader to the exit.
You'll notice that you are under attack as soon as you start this level. To calm your enemies down, swim around the boulders and use your sonar on them (try hugging the cave walls to avoid major damage). As soon as you hit what appears to be a dead end, look up and jump over the wall to the next cave and be on your way until you reach the central chamber.
To exit this chamber, you must find the Glowing Orb. Find the help glyph and head left until you find a cluster of houses. Swim behind the houses and you'll see the Glowing Orb (if you have a hard time finding it, look at the wall and let the faint glow guide you).
As soon as you touch the Glowing Orb, the cave will come under attack and you must find the exit. Talk to the Rebel Leader swimming near the reflective rocks and he'll show you the exit, but first you must take care of the dolphin attacking him.
Enemies Coming Out of the Walls
This is one of those extremely frustrating points in Ecco and the best you can do is get used to the layout and the enemies' pattern. It is a good idea to survey the path ahead and understand what you are up against before leading the Rebel Leader down the cave. Use your sonar map and swim all the way down the cave. The map will show you where the Clan dolphins are hiding. Learn where each cave is and go back to get the Rebel Leader (you just have to swim next to him and he will start swimming with you). The trick is to stay slightly ahead of him and dash attack the Clan members as soon as they leave their hiding places (you only have to hit the Clan member once). Remember, if the Rebel Leader gets hit once, he will swim back to the entrance and you'll have to start the whole thing again.
Once you get past the first four Clan members, follow the Rebel Leader into the hole in the rock and get ready for the last leg of this cave. The good news is that this is a checkpoint and the Rebel Leader will return here when he gets attacked. The bad news is, there are four more Clan members you need to bypass before getting to the last stage of this level.
The Giant Croc
This is actually one of the easiest bosses in the whole game. As soon as your reach this area, swim close to the ground and through the spikes until you reach the Sonar power-up. Stay where you are and look up. Aim your sonar at the ceiling spikes and keep firing until one falls on the giant crocodile. When one of the spikes hits the giant crocodile, it will show you the exit.