Ocean Realm
The Ocean Realm is the name of the southeastern quadrant of the re-established land of Hyrule and the third region visited by Link in Spirit Tracks. As is implied by its name, much of this part of the country is composed primarily of water from an ocean, presumably the Great Sea, with the coastline running along the northern border of the region and several small islands dotting the surface of the ocean. It is home to the settlement of Papuchia Village as well as the Ocean Sanctuary, home of the realm's guardian Lokomo, Carben. The region is often plagued by pirate attacks and is also home to the Ocean Temple, one of the four special temples scattered across Hyrule that powers the Tower of Spirits. Link comes to this region after claiming the Ocean Rail Map from the Tower of Spirits in the hope of meeting with Carben and restoring the lost Spirit Tracks of the Ocean Realm in order to reach the Ocean Temple.
Spirit Tracks
The Ocean Temple, one of the four temples that provides power to the Tower of Spirits and thus sustains the existence of the Spirit Tracks, is located within the southeastern section of Hyrule known as the Ocean Realm and has been cursed with the presence of a horrible monster known as Phytops in order to disrupt the temple's energy beacon and stop energy from flowing to the Tower of Spirits. With this, the temple's energy beacon was deactivated and its Force Gem stolen by the octopus-like beast, weakening the Tower of Spirits and causing the Spirit Tracks all around the Ocean Realm to vanish, cutting off access to the underwater entrance of the temple.
After purging the Snow Temple of the vile presence of Fraaz, Link headed toward the third region of the country he had not visited yet, the Ocean Realm. However, he finds that the bridge leading from the Forest Realm into it has been damaged and must be repaired. Linebeck III of the Linebeck Trading Company instructs Link to find the Bridge Fixer who lives in the Snow Realm in order to have the bridge repaired. Link brings the Bridge Fixer to the broken bridge, and he agrees to fix it, but on the condition he be paid 5,000 Rupees for his services for fixing the bridge as well as back-pay for work he did on Linebeck III's home. To pay the Bridge Fixer's fee, Linebeck III gives Link a letter written by his grandfather detailing where he had hidden a very valuable relic known as the Regal Ring, worth approximately 8,000 Rupees. Link succeeds in finding the ring and gives it to the Bridge Fixer as his payment.
Within the Ocean Realm itself, Link visits Papuchia Village and goes in search of the Ocean Sanctuary to meet with Carben, the guardian Lokomo of the realm, in order to restore the Spirit Tracks of the Ocean Realm. However, Link finds Carben missing from the sanctuary and returns to Papuchia Village, where he finally meets with Carben and takes him back to the Ocean Sanctuary, where the pair enter into a duet with Link playing the Spirit Flute, causing the lost tracks to reappear. The young hero then battles pirates as well as sea monsters to travel around the surface of the Ocean Realm and activate three special switches to restore the entrance leading to the underwater parts of the Spirit Tracks, which in turn lead to the underwater entrance of the Ocean Temple.
Link enters the temple and battles many water-related beasts and traps in the hope of discovering why the temple has stopped transmitting energy to the Tower of Spirits. Working his way through the large structure (extending both underwater and above the surface), the young hero is able to discover the Snake Whip, the temple's treasure. With this treasure in hand, Link is able to conquer the trials of the temple and work his way to the top of the temple, the part that rests above the surface and serves as the chamber of the temple's energy beacon. It is here that Link discovers the Barbed Menace Phytops, the beast responsible for the tainting of the temple. With the Snake Whip and his arsenal of weapons, Link is able to destroy the beast however, recovering the temple's Force Gem and restoring it to the temple's energy beacon, thus restoring more energy to the Tower of Spirits and completing Link's quest in the Ocean Realm.