The Water Tram is a fast travel creation which only requires water, a boat, and pressure plates. A water tram can involve a complex delivery system, where you get a fresh boat every time you go there, or it can be as simple as a 2x3 tunnel. But a water tram absolutely requires pressure plates. Otherwise, it will just be a water tunnel, and while you can reach high speeds with it, you cannot get a massive burst of speed. But here is where the water tram's special system comes in.
The water tram relies on water currents to get it at a high speed, but since water only goes eight blocks, you need multiple water currents. But, if you just place random water sources at random intervals, you will go into a current going backwards from where you want to go, so you don't get anywhere, at least on the boat. Or very slowly. However, pressure plates cannot have water going over them, like ladders and signs, so this is a key part.
What you do is make an infinite water spring, which you can easily do with 2 buckets of water. Then, you fill your buckets with water, and set off. You build your tram road so it is two blocks wide for the water part. Then, you put two water sources at one end, let it flow for several blocks, then place two pressure plates to stop the flow. Then, you place two water blocks after the pressure plates, make sure to keep it exactly after, and do it again, and again, until you can cross great distances at ease. The best setup is to have 5 water blocks per section (1 source + 4 flowing); any more than that and your boat will hit the side of a pressure plate and break. It's also the fastest, traveling at about 7.7 blocks per second (192 blocks in 25 seconds) - 35% faster than sprinting, and without the hunger drain. If signs are used instead of pressure plates, sections can have up to 7 water blocks, but this does not significantly increase speed, and requires more resources. Making the sides of the road out of pressure plates as well is recommended; boats will break if they hit full or half blocks.
Making two parallel roads in opposite directions allows easy two-way transportation. The pressure plates can be connected to redstone circuitry and act as motion sensors.
Diagram
Notes:
- You can use any block as a wall, but this example uses cobblestone.
- Water flows into the empty spaces.
Video
With an appropriate mod installed, the same technique can be used with lava and minecarts. However, it isn't much faster than walking, even in the Nether, and not nearly as safe.
Glass panes
It is possible to make water trams that use one-wide water stream with glass panes on both sides. This is more resource-friendly, but it has a greater chance of breaking your boat.
1.2.3 and later
Gjrud has developed water trams that work in both multiplayer and single player. The basic idea is to use single-wide streams (instead of double-wide streams), with wood fences on the sides. Gjrud has stated that wood fences, despite the larger hit boxes (or perhaps, because of them) work better and more reliably; however, the inside of every turn must be changed to a pressure plate. The problem with 1.2 deals with boat damage—multiplayer boats are very fragile, and any turn has to have a "brake"—a length 2 (if you are at slow speed) or 3 (if you are at high speed) water flow in the "wrong" direction to bring your speed down and prevent the boat from falling apart. In addition, there are occasional needs for oddities—either 2 adjacent plates, or similar—to deal with occasional issues. See his video for more details. With the introduction of snow and Ice it is not advisable to use this method of transport in tundra/taiga biomes due to the source water freezing and destroying the boat unless one places glowstone underneath the source blocks.
With the major change in boats that happened in the 1.9 update, water trams/EATS roads no longer function correctly. A better alternative to water trams are "ice roads", which allows for fast travel through boats and ice/spiked ice. "Ice roads" can also work in The Nether.