Endless Ocean

Wait until after 6 p.m. in the game for sunset. Sit on the deck chair on the boat and look at the horizon to see the game's credits. Note: To check the time in the game, look at the lock in the boat's cabin.
naie nvopvdo esfrfhru

Another way to see the end credits is to find the large animal that Kat calls the "Ancient Mother".

At Ship's Rest at night after you've found the Shark Tooth.

When you come across a dolphin that is not your partner, Catherine will prompt you to befriend it. Make friends as usual by patting, nudging or whistling to find more information about the creature. When you have two bits of information (you will need to come back on a different day for the second) the dolphin will appear at your boat the next time you return. Use the Ramp and you will have the option to make it your partner. If you have three partners already you will be prompted to get rid of one of them to make room for the new. The next time you return to the boat the rejected partner will visit to seek reinstatement or say goodbye. Once you have given your new partner a name they are ready to be trained or to be used when diving.

Complete the indicated task to unlock the corresponding song.

The Water is Wide: Unlocked by watching the credits.
Shenandoah: Unlocked by entering "The Great Aqua Cave".
River of Dreams: Unlocked by entering the White Room of "The Great Aqua Cave".
Pokarekare Ana: Free the bottlenose dolphin from "The Lagoon".
Hine e Hine: Cave in the roof of "The Ruins".
E Pari Ra: Unlocked by visiting "Ship's Rest".
Benedictus (Hayley Westenra): Unlocked by visiting "The Abyss".
Amazing Grace: Unlocked by visiting "Mo'ia Atoll" ruins.
Hayley's Medley: Unlock all the other songs.
Hayley's Medley song consists of all of Westenra's songs in random order.