Find Sen

Location
Talk to Doug, on Castaway Rock.

You must first have completed the quest Give A Man A Fish.

Go See Sen

 * 1) Crouch under the log behind Doug to get to the other side.
 * 2) Talk to Sen.

Secrets Inside Secrets

 * 1) On the back of the first ruin wall left of the giant log, there is a lever. Pull it
 * 2) Along the wall near Doug there is a small hole surrounded by vines, enter it and go down the shaft
 * Be prepared, there is a Big Crab waiting for you
 * 1) At the end of the cave is a Platform with a chest. Open it and pick up the
 * 2) Leave the Cave the same way you entered it
 * There is a second lever to open the door again
 * 1) Activate the sun-shaped switch next to Sen

Reporting To Sen

 * 1) Talk to Sen

Escape the Island

 * 1) Complete the quest Tinkerer's Assistant to get the
 * 2) Equip the Glider and fly off the island
 * 3) Find Sen outside the Hope Harbor on Azura Island
 * 4) Talk to him