The Boatman was a Sangheili elder

Early during the formations of the Covenant Empire, this Sangheili ferried Fal 'Chavamee, an Arbiter, up a small river on Sanghelios. He dropped off 'Chavamee in an opening along the river's edge, warning him that the trail he was going on was dangerous; which he was later proven correct, as a group of Sangheili soldiers confronted the Arbiter.