This part will take you through getting to Mercay Island Harbor.
Path to the Harbor
Now take the path up north where the sign is, and again we'll see the Red Chuchus we encountered earlier. Just simply strike them down with the sword, then proceed up toward where the Gossip Stone is, then to the right and down. The cave entrance we need to enter is blocked by trees, so slash them out of the way with the sword.
Inside the cave, proceed up and to the right, throwing the rocks out of our way, until we come to a locked door. Then continue to the right, fighting the Red Chuchus that are in your way, then climb the stairs toward the chest where you'll find the small key to open the door. In the room that we enter past the door, there are four switches on the north wall, two on the left of the locked door and two on the right. Slay the Chuchus, then go over and read the stone tablet on the left next to a block that we'll need to push to enter the room on the left. Slay the Keese in the room, then read the stone tablet in the room. It will give you a clue as to which switch you need to pull in what order. Remember the clue and mark it on your map. Then go over toward the room on your right, push the block out of your way, slay the Keese, and read the stone tablet that will give you your next clue for the switches so you can mark them on the map. Then go back into the center room and pull the switches in the correct order. (If you need to know, it's center left, far left, far right, center right.) A small key will fall into the center of the room if you did it correctly; otherwise, purple wormlike insects will fall into the room. Grab the key and open the locked door, then head up the stairs to the...
Slay the purple rats and go north until you reach the locked door, then go to the left and slay the rats there. There will be one rat that will be difficult to slay that keeps going back and forth between the caves through a mouse hole. That rat also carries the small key that we need. Take the block found in the far left area of the cave, then push it over the front of the mouse hole to block it. The rat will now only come out of the mouse hole on the right side, but will still be difficult to slay. Wait until he pops out of the hole and runs into the far left part of the cave, then corner it and slay it. You now have your small key. Open the door and travel the path that goes up to the right and then down, slaying the Keese along the way as you go, and then exit.
Mercay Village Harbor
We're now at the harbor town of Mercay Island, so our next job is to find Linebeck. Go over to the port on the southeast part of town (where the boat is) and talk to the man who will comment on the boat and its captain, who then says he's seen him at the Milk Bar. Go over to the Milk Bar (it's the house north of the one on the southwest part of town) and talk to its owner about Linebeck, and he will tell you he's gone off toward the Temple of the Ocean King. He will point out the location of the Temple on your map (it's the only big structure there is on the island), so head out of town and take the path on the north end to the Temple.