PURPOSE: To improve the safety of light buoy by providing a plurality of partitions in the buoy body separated by circular wall and radial wall thereby limiting the damage due to the collision with such as vessel to a portion of said partition.

CONSTITUTION: Circular liquid tight walls 11, 12 are provided concentrically in the buoy body 1 then they are partitioned by a plurality of radial liquid tight walls 13, 14, 14' to provide a plurality of partitions 15W17. Independent bubble blowing material is filled in the outermost partition 15 to provide the floating chamber, while the partition 16 is used as a fuel tank or ballast tank and the innermost partition 17 is used as mechanical room for such as generator 18.