Pyrococcus abyssi is a hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent in the North Fiji Basin at 2,000 metres (6,600 ft).

It is anaerobic, sulfur-metabolizing, gram-negative, coccus-shaped and highly motile.

Its optimum growth temperature is 96 °C (205 °F).

[1] Pyrococcus abyssi has been used as a model organism in studies of DNA polymerase.

[2] This species can also grow at high cell densities in bioreactors.