BIOS-3 is an experimental closed ecosystem at the Institute of Biophysics in Krasnoyarsk, Russia.
Its construction began in 1965, and was completed in 1972. BIOS-3 consists of a 315 cubic metres (11,100 cu ft) underground steel structure suitable for up to three persons, and was initially used for developing closed ecological human life-support ecosystems. It was divided into 4 compartments, one of which is a crew area. The crew area consists of 3 single-cabins, a galley, lavatory and control room. Initially one other compartment was an algal cultivator, and the other two phytotrons for growing wheat or vegetables. The plants growing in the two phytotrons contributed approximately 25% of the air filtering in the compound. Later, the algal cultivator was converted into a third phytotron. A level of light comparable to sunlight was supplied in each of the 4 compartments by 20 kW xenon lamps, cooled by water jackets. The facility used 400 kW of electricity, supplied by a nearby hydroelectric power station.