Like it states just pass the Undercaves without dying. If your having trouble save often and on different spots so if you mess up you can load a earlier save.

In The Vents level you will find a dolphin at the start that if you talk to him, he will ask you to find 3 of his missing pod members. Find them, bring them back and the achievement is yours. If your having trouble, the link below is a map that has the mission dolphin marked as a BLACK square and the lost pod members as WHITE squares.(Thank to www.ecco-darksea.com for the maps.)

All the way on the right side of The Lagoon level you will find yet another dolphin that is missing 3 pod members. Find them, bring them back and the achievement is yours. If your having trouble, the link below is a map that has the mission dolphin marked as a BLACK square and the lost pod members as WHITE squares.(Thank to www.ecco-darksea.com for the maps.)

You have to play through the entire game start to finish 2 times. You CANNOT save right before the last boss beat him once load and beat him again, that will not unlock the achievement.

Reach the Ridge Water level without dying. Use the save method mentioned in Undercaves Survival and it shouldn't be a problem.

When your reach the first level with sharks kill 10 of them in a row without killing any other enemies.

After you get the Death Sonar form saving the dolphins on The Vents level, kill 30 enemies throughout your game using Death Sonar. Death Sonar is used by pressing then quickly after. That makes your sonar wave act like a bullet.

At the end of the Undercaves there is a large octopus waving a tenticle, swim very slowly and straight past him both ways and he will not hit you. Finish the level and you will unlock the achievement.

This one was tricky, you have to swim all the way to the rockwall on the left. Line up with the plants coming out of the water just to the right of the wall. Aim northwest out of the water and let the sonar fly. There are 2 hidden glyphs over there so if you hit the wrong 1 first, keep trying its in there too. In the link below is a map with the approximate location in the rockwall to aim for, the glyph is marked as a WHITE square.

Like the description says beat the game dying no more then 3 time throughout the game. If your having trouble save often and on multiple saves so if you mess up on one, you can load an earlier save.

On The Vents level DO NOT save the dolphin's 3 pod members, then make it to the Dark Water level and the achievement will unlock.

You can find this glyph right about the middle of the map, just after you come acroos a killer whale you can speak with. If your having trouble finding the glyph, the link below has a map with the glyph marked as a WHITE square.