A log boat is a boat which is made from a single log which has been hollowed to reduce the weight of the log so that it will maintain buoyancy. The hollow also creates room for passengers and cargo. Log boats are among the oldest boats known to have been used by human societies, with a number of extant examples which are thousands of years old; log boats probably survive to be found by archaeologists because of their relatively solid and dense design, and it is entirely possible that other boat designs are almost as old, and simply haven't endured to be found.
Also known as a dugout or monoxylon, the log boat has been independently invented by a number of human societies, some of which continue to use log boats to this day. Log boats can be constructed by creating a controlled fire inside a large log to hollow it out, or by carving out the log with the use of metal tools. For stability and additional room for cargo, the boat may be fitted with outriggers, and the boat can be controlled with paddles, poles, or sails, depending on the preference of the person building it.
In order for societies to build log boats, they need access to trees which are suitable for building. In addition to simply being big, the tree used for a log boat also needs to have relatively lightweight wood for maximum buoyancy, and some cultures have had specific taboos about particular tree species which limit their construction options. Log boats may be made from trees which are felled specifically for the purpose, or from trees which have fallen naturally, as long as fallen wood is recovered before it begins to rot.
The crudest log boat may be a simple hollowed log with a coarse interior, while more complex versions may be elaborately carved and painted. The craftsmanship of some traditional log boats is legendary, especially those of the Polynesians, which were used to successfully explore much of the South Pacific in journeys which crossed vast expanses of open water. Several modern expeditions in the 1970s attempted to repeat the sailing accomplishments of the Polynesians using similar craft, and illustrating how remarkable these journeys were in an era before sophisticated navigation instruments, high-tech boats, and the support of aircraft and search vessels in the event of an accident.
In addition to being used for navigation and cargo transport, a log boat can also have ceremonial uses. Some seagoing societies have traditionally buried high-ranking members of society with log boats packed with useful grave goods, or conducted burials at sea by launching their dead in log boats. Boats for ceremonial use tend to be much more ornamental, and they may be less structurally sound, and in some cases actually intended to sink.