Outboard drive for boats

Outboard drive unit for boats for driving at least one propeller, comprising, firstly, an underwater housing (6) in which a drive shaft (16), which in the operating state of the drive unit is essentially vertical, is rotatably mounted and which, via a bevel gearing (19, 20, 21) is drivably coupled at a lower end to at least one propeller shaft (7, 8) mounted in the underwater housing, and, secondly, a gear housing (11) joined to the underwater housing and enclosing a second bevel gearing (13, 14, 15), via which the upper end of said essentially vertical drive shaft is drivably coupled to an at least substantially horizontal shaft (12), and mounting elements (23) for mounting the drive unit with the underwater housing on the outside and the gear housing on the inside of a boat hull, characterized in that a lubricating oil chamber (33) is arranged between the underwater housing (6) and the gear housing (11), said chamber being bounded by a space (36) through which surrounding water flows.