Fluvionectes (meaning "river swimmer", from both Latin and Greek) is a genus of elasmosaurid plesiosaur found in the Dinosaur Park Formation in Alberta, Canada.

[1] The holotype specimen of Fluvionectes is a partial skeleton preserving an osteologically mature, likely a young adult individual that would have reached 5–5.2 m (16–17 ft) long and weighed 392 kilograms (864 lb).

[1][2] A more mature, larger, but more fragmentary specimen (TMP 2009.037.0007) is also known, consisting of a partial rib and gastralium, and left humerus, indicating that this taxon may have reached 7 m (23 ft) in maximum body length.

[1] Fluvionectes appears to have been a freshwater and brackish water animal based on its discovery from a non-marine to paralic sedimentary unit.

[1] The holotype was discovered alongside many pieces of coalified wood, which is interpreted as the carcass having been caught in a log jam.