SSCV Sleipnir is a semi-submersible crane vessel (SSCV) owned and operated by Heerema Marine Contractors. It is named for Sleipnir, the eight-legged horse ridden by Odin in Norse mythology.

The vessel is equipped with two revolving cranes built by Huisman Equipment B.V., each with a capacity of 10,000 t (11,000 short tons); the main cranes can be operated in tandem to jointly lift 20,000 t (22,000 short tons). It was ordered in 2015 and built in Singapore by Sembcorp Marine. After its completion in 2019, SSCV Sleipnir succeeded Heerema's earlier SSCV Thialf as the largest crane vessel in the world.

The vessel is essentially a large platform supported by eight columns (four on each side), with one pontoon per side. Typical SSCVs use larger columns under the cranes to provide support, which can lead to severe pitching in rough seas; SSCV Sleipnir uses columns that are symmetrical fore and aft for calmer motions under higher sea states. The columns are rounded to reduce wave interactions, and the pontoons are streamlined to reduce drag.

The two large port and starboard tub-mounted cranes are provided by Huisman; overall boom length is 144 m (472 ft). The slewing system, which allows the cranes to rotate in their tub, uses the world's largest bearings at 30 m (98 ft) in diameter. Conventional tub-mounted cranes ride on bogies or wheels, while the Huisman 10,000t cranes use the bearing directly. Prior to the cranes for Sleipnir, the largest bearings Huisman had used for tub-mounted cranes were only 12 m (39 ft) in diameter. The crane house is secured to the foundation using 1,100 bolts 82 mm (3.2 in) in diameter, held in place by nuts weighing more than 40 kg (88 lb).