The Castoro Sei (Italian for Beaver Six) is a column stabilized semi-submersible pipelay vessel. She has an overall length of 152 metres (499 ft), a width of 70.5 metres (231 ft) and an operating draught of 7.8 to 15.5 metres (26 to 51 ft). The Castoro Sei is equipped with 2 rotating gantry cranes 134 tonnes capacity and three 130 tonne pipe tensioners for pipelaying. She provides accommodation for 354 persons.She was built in 1978 by Fincantieri, and owned and operated by Saipem.