| Named By: | Harry Govier Seeley in 1874 |
| Time Period: | Callovian to late Tithonian |
| Location: | England, Dorset - Jurassic Coast, Kimmeridge Clay |
| Size: | Uncertain due to incomplete fossil materia |
| Diet: | unavailable |
| Fossil(s): | Only partial post cranial remains including vertebrae, ribs, limbs, and parts of the shoulder girdle |
| Classification: | | Chordata | Reptilia | Sauropterygia | Plesiosauria | Plesiosauroidea | |
Colymbosaurus is a genus of cryptoclidid plesiosaur from the Late Jurassic (Kimmeridgian-Tithonian) of the UK and Svalbard, Norway. There are two currently recognized species, C. megadeirus and C. svalbardensis.