Ecco The Dolphin Wiki
Learn from the 'Teacher', free the baby whale from a rockslide, win 'Fish Fetch'.
When the level starts, talk to the 'Teacher' until you have learned everything
he knows.  After that, swim to the group of three dolphins.  One of them will be
the 'Coach', who will inform you that they are playing a game of 'Fish Fetch'.
He will ask you to collect a fish that is coloured either Yellow, Red or Purple,
and return it to him.  After playing the game once, use your sonar map to locate
the whales.  Talk to the mother Whale, then return to the area where the
'Teacher' is.  A cut-scene will take over and show The Foe breaking through the
Guardian's shield, and cracking the Guardian itself.  This will unleash an
earthquake that will bury the gate back towards Atlantis.

After this has finished, relocate the whales on your map and swim back to the
mother.  You will notice the baby has gone.  The mother will ask you to help
find her baby.  If you turn so that you are facing the Whale sideways on, with
her head pointing left, and then turn around 180 degrees.  Swim towards the
wall, then follow the wall to the left, so that the wall is on your right hand
side, you will come across a rock fall with a green rock at the bottom of it,
with the baby Whale behind it.  Swim inside the rock fall and talk to the baby,
then return to the area with the 'Coach'.  Just as you get near the area the two
'Players' will swim over to you and line up beside you.

Go back to the baby Whale and guide all three dolphins towards the
aforementioned green rock at the base of the rock fall.  A cut-scene will show
Ecco and the 'Players' moving the rock, which will shift the larger rocks out of
the way and allow the baby Whale to escape.  Once this sequence has finished and
the baby has returned to its mother, go and talk to the mother and she will ask
you to go towards the waterfall.  Once you go towards the waterfall the game
will take over and show the mother Whale swimming over and blocking the current
of the waterfall, allowing Ecco to leave and gain access to Perils Of The Coral
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