Boat

A boat is an item and vehicle entity. Boats float and move easily on water, and can be ridden, so they allow fast transportation in Ocean Biomes or any large area of water; however they are quite fragile and easily destroyed by running aground. Boats can be pushed around by water currents, allowing automatic transportation and boat storage, and the use of boats as mechanism components. Notch said that he'll try to make "fancy huge customizable boats."

Once crafted, a boat may be placed anywhere in water, or on land by right-clicking. Once placed, it can never be recovered; if you "punch it down" or crash it (or use an axe), it breaks into sticks and planks. You can place a boat in lava, but if you try to ride it the boat will break and you will fall into the lava and start taking damage.

Riding boats
Like minecarts, a boat may be right-clicked to enter or exit. Boats can be entered from any direction, including below (which is useful for getting to the surface slightly quicker after diving).

Boats move according to the player's control or water currents. Boats move significantly faster than a player can walk on land or water, but are slower than minecarts. If on land, a boat may still be controlled but extremely slow.

Boats are controlled by the player's movement keys: they will accelerate slowly in the same direction the player would move if they were not in the boat. Boats also turn to always face in the direction of movement, turning you with them. For example, pressing the forward and right keys, or pressing the forward key while you face slightly to the right, will result in moving in a circle as the boat swings to the right, continuously changing your “push” direction. When moving fast enough, there will be "water spray" visual effect representing the bow wake.

If you move through an area with only 1 block of air between the water and ceiling, you will take suffocation damage, but can still move anywhere the boat can.

Boat physics
Boats are entities. Boats behave much like off-track minecarts; they can be pushed around slowly on solid blocks, are easily pushed around by water currents, and always face the direction they last moved.

If a boat runs into another entity such as a player, another boat, or a mob, it will bounce off and change direction; running into a block will merely stop movement (if the boat does not break). If you crash a boat into another boat, the boat being ridden will be destroyed while the other one will just bump away.

Boats are annoyingly fragile; they take damage by being hit or crashing into blocks at high speed. After taking enough damage over a short interval, the boat will break, dropping 3 Wooden Planks and 2 Sticks. Although boats are easily broken while traveling horizontally, they do not take damage from falling.. Sneaking while on a boat will prevent you from going fast enough to break the boat on impact with a solid block. Since they do not drop boat resources, boats cannot be picked up and reused like minecarts

Boats do not break when running into Soul Sand at water level, because Soul Sand has a lower top surface so that the boat merely runs aground rather than crashing, so it is useful to make docks and harbors out of Soul Sand. Though Soul Sand now has the same bug as slabs, when you exit a boat while on Soul Sand, the player will take falling damage, usually enough to cause death.

Doors can be used to control the movement of boats, such as blocking them into docks or preventing them from following a current until the door is opened. This technique is often used to build boat dispensers.

Whilst boats used to float upwards in any type of water, flowing or not, downwards flowing water will now cause them to become stuck on the bottom, making many water-elevator devices useless and risking the player drowning. A water elevator constructed solely of source blocks still works, although a bit slower than water elevators before.

Canals
Canals, consisting of a series of trenches dug on land filled with flowing water, are a possible method of transportation across large distances using boats. A canal transportation system is more time-consuming to construct, but more energy-efficient than a rail transportation system. Double doors, fence gates, ladders, pressure plates, and sugar canes can be used as consecutive locks on the canal to control the direction of the flow of water in a canal to construct a flowing fully horizontal waterway. Locks can also be used for boat lifts (Water Elevator or Water Ladder) between different elevations of water. (For real life examples, see Wikipedia's canal, lock (water transport), and boat lift.)

It is also possible to construct a canal with still water by strategically placing water in a diagonal line. This makes for faster transportation.

It is also possible for a boat to act like a minecart and also has the same speed as a fully powered minecart that you can make into a loop with a series of "land breaks" for turning without breaking the boat. See the video here.

History
Boats first appeared in the Seecret Friday Update 5 of Alpha. As of Beta Version 1.8, it is possible to score a Critical Hit against a Boat. As of the Beta 1.6.6 update, crashing into soul sand on a boat will kill the player, but keep the boat intact.

Bugs

 * In many multiplayer servers, typing /spawn will cause other players to see the player in a boat, while the player may move around invisibly. The player's legs would still be separated, as if they were in a boat. Any changes to blocks that the player makes during the glitch do not affect other players.
 * When entering a portal while sitting in a boat, the game will crash.
 * There is a glitch where if you place a boat on top of glass, get in, and break the boat you will fall through the glass taking 1 heart of damage.
 * When placing a boat on ground, not water, the graphic for splashing water still appears.
 * If the player exits the game while on a boat, the boat will be far away and the player will fall into the water upon reloading. There will also sometimes be a line of boats in the path you were traveling in. (Proven in 1.2.5 survival)
 * When entering/leaving a boat while holding a bow, the action of right-clicking will also fire an arrow (if the player is carrying arrows).
 * If you are holding a boat and try to open a door, the boat will be placed on top of the door.
 * Crashing into any animal in a boat can kill the player, keeping the boat intact. It can also crash the game.
 * Similar to the above, running aground on slabs will inflict some amount of falling damage. The damage seems to be much worse the longer you've been in the boat. (Perhaps due to the bobbing motion at sea being counted as 'falling' distance, and cashing it all in at once). This bug is also triggered when exiting a boat while on Soul Sand.
 * When right-clicking on an existing boat in the water with a boat in your hand, you will enter the boat and be propelled through the water at a high rate of speed.
 * If a boat is placed onto a rail the boat will stay inside of the block above the rail until the boat takes enough damage.
 * When you middle-click a boat while in it, the client crashes.
 * If you sail a boat into a space in which only one block of space exists above the water, above which is a solid block such as Dirt, you will begin to suffocate.
 * When you place a boat in the middle of a 1x1 canal, it will get stuck and disappear.
 * As of 1.0.0 (tested in prerelease 11w50a), a boat that does not have a player in it does not follow the physics of water.
 * In versions Beta 1.5 and earlier, if you made a 3x3 hole that is three blocks deep, put a boat or two in the hole, and fill the hole with sand or gravel it would make quicksand.
 * If you sail a boat into a Lily Pad the boat breaks.
 * If you sail a boat into a Squid the boat breaks.
 * In multiplayer, boats will move very slowly and laggy.
 * If you ride a boat on water, when you move, there will be water inside the boat.
 * If you are in a boat and go into thirdperson, your leggings will be in the position as if you were standing, and you will have another pair of legs in a sitting motion. Both pairs of legs clip through the boat.
 * Squids, if close enough to the boat, will head to the boat, as if they are trying to attack it. Since Squid can break boats, the player should be cautious when sailing.
 * If an upside-down Slab is placed over water, the boat will be able to travel underneath it without suffocating the player.
 * sometimes, if you sail a boat into a portal, it will multiply into 5 of itself in random parts of the chunk
 * If you have a boat in your hand while exiting a boat, you will place a second boat down.

Trivia

 * Boats can be controlled on land, albeit very slowly.
 * Boats being pushed over snow will make the snow disappear.
 * Boats can be stood on like blocks, and the player will not fall through them.
 * It is possible to get out of a boat and "surf" on it while it is moving, by sprinting foward.

Gallery

 * A video of boat riding
 * A video of a simple boat elevator for transportation
 * A video of a boat placed on lava