Rust, the multiplayer survival game from Facepunch Studios, left Early Access back in February but is still receiving updates and additions (which makes sense since creator Garry Newman still considers Rust to be in alpha). Chugging into Rust in an update this week is its first player-controlled vehicle, a motorized rowboat. Boats are not craftable, so you'll have to go out and find one: they will spawn along the coastlines of the island map. The boat has room for a driver and up to three passengers.
Boats require low grade fuel to power their motors, and if left out in the elements a boat will decay in about three hours. If you find one and want to keep it you'll need to build a boathouse, this post on Rust's devblog advises. Servers may spawn as many as 64 boats at a time, so it doesn't sound like they'll be in terribly short supply, however.
To give you a little something to do on your boat, servers will also spawn floating piles of junk on the open water, so you can do some looting while you're cruising around. There's a compartment built into the bow of the boat to store your haul. Boats can sink, naturally, if they take too much damage, but they can also be repaired with a hammer, wood, and metal fragments.
You can find lots more info about Rusts's boats in this post on Rustafied.