Build a Raft
To build your raft, you must first use a "Gathering Axe" to gather firewood from the trees near the pier. If you don't have an axe, you can purchase one from the NPC next to the pier. Gather 10 units of firewood and bring them to the NPC at the pier; he will build a raft from the firewood you collected. The raft will be tethered to the pier when it's ready for you to use.
Rent a Raft
If you don't like the idea of gathering wood, you can rent a raft from the NPC at the pier. This method will cost 5000 gold, however, so it might be worth your time to gather the wood and build the raft. If you do decide to rent, talk to the NPC and pay the gold; the raft will appear at the pier for you to use.
Start the Ride
Once the raft has arrived, you can load up your raft with party members and be on your way. Only party members may ride the raft, and only eight players can fit on a raft, so choose your companions carefully. When you're ready to go, click the rope that connects the raft to the pier.
Playing the Game
While on the raft, hobgoblins will periodically attack your party. The more hobgoblins you kill, the more stars you'll earn. At two points during the minigame, you can choose to rest, and you can exchange your earned stars for items like bandages if desired. If you choose not to exchange stars, they will remain with you through the end of the minigame.
Rewards
If you've earned 20 stars at the end of the minigame, you will gain the title of "Chief Mate." You will also be given a choice of four other rewards. If you choose to keep your stars, you can keep them for the duration of your stay in the La Terra Highlands Courcle, but you must use them before you leave the area, log out or board another raft.