Head north and read the sign. It says that this is the Wayfarer's Island. Keep
following the path and defeat the enemies, then go all the way right and enter
the cave there. Inside, follow the path to a crack in the wall. The sign says
that it leads to a mini-game. Blow up the crack and follow the path, breaking
the pots for Rupees. Exit the cave and you'll be on the other side of the
island. Go right and read the sign, which says that this is the Cannon Game.
You can play it for 20 Rupees; refer to the Mini-Games section to see how to
play it. Go back into the cave and go back to the other side of the island,
then head north and enter that building. Talk to the old man inside and listen
to his mindless gossip. He'll tell you about a mermaid.
Once he finishes talking, exit the house. Now, kill every single enemy on the
island if you haven't already, then look around the waters until you spot a
mermaid. When you approach her, she'll move to a different location. Don't get
too close to her, then throw the Boomerang at her to hit her head. She'll admit
to dressing up as a mermaid, and not actually being one. Apologize to her, then
she'll say that she'll go visit the old man. Go back inside the house and talk
to him again, then tell him you found the mermaid. He'll babble on and say that
she probably went with another man. Exit the house again and Ciela will think
that she's with Linebeck. Go talk to Linebeck and he'll say that the mermaid
appeared, but then disappeared before he got the chance to say anything.
Now, go back and visit the old man's house again, and the mermaid will be in
his pool. Talk to him and he'll thank you for bringing the mermaid here, then
he'll give you a Fishing Rod as a reward. While out at sea, sail to a fish
shadow on the map and tap Menu, then Fish. See the Fishing section of the guide
for more information on it. Go back to Linebeck and tell him you're ready to
Set your course directly south, to the Southwestern Sea. Once there, set your
course for Mercay Island.