Riser bundle

A riser bundle comprising a number of risers (2) extending in a wave configuration from the bottom of a body of water up to a floating structure, the riser bundle (1) along its length being provided with means giving different portions (5, 6, 7) along the wave configuration different submerged weight and net buoyancy, characterized in that the risers (2) are arranged around a centrally extending tube (3) and are surrounded by a tubular outer casing (4), the central tube (3) and the interspaces (8) between the risers (2), between the central tube (3) and the outer casing (4), along different portions of the wave configuration in operation being filled with materials of different density, for achieving at least one light portion (5) of the configuration having a desired positive net buoyancy, and a heavy portion (6 resp. 7) on each side of the light portion (5) having a desired positive submerged weight.