A member of genus Hygrotus STEPHENS, 1828, subgenus Coelambus THOMSON, 1860 is recorded for the first time from Hawaii which belongs to the Pacific zoogeographical region: Hygrotus nubilus (LECONTE, 1855) which so far has been known only from the USA and Canada (and thus from the Nearctic zoogeographical region) was found on Mauna Kea Volcano on the Island of Hawaii. Collecting data of the specimens studied are given and the habitus as well as the male and female genitalia are illustrated. Possibilities for the source of introduction of this Nearctic species to Hawaii are discussed. The species has been also found for the first time in northern Mexico (Coyame, Chihuahua State) and, thus, in the Neotropical zoogeographical region. Keywords: Coleoptera, Dytiscidae, Hygrotini, Hygrotus nubilus, Hawaii, Mexico, first record Fig. 1, p. 1306 Lake Waiau, Mauna Kea Volcano on the Island of Hawaii; (photo by Th. Tunsch; available under <https://web.archive.org/web/20161025081343/http://www.panoramio.com/photo/81368979>) (copyright: © CC BY-SA Thomas Tunsch (th-t.de) / www.panoramio.com/photo/81368979)