Exploring Carroll Island

Head to Carroll island and hit all the checkpoints along the way. Once you have all the checkpoints accounted for, return to Sevrin Lockhand - Checkpoint - Checkpoint - Checkpoint

"You didn't do too badly, so I guess that means you've proven yourself. I will to let you fill one of my charters, and we'll split the profits. How does that sound? Sail these people out to Carroll Island. They're interested in some property I own there. Get them back here in a timely fashion and I'll give you some silver."