A total of 168.4 hours of visual cetacean survey work was carried out in association with two geophysical surveys in Montserrat waters (eastern Caribbean) during December 2007 and May 2010, using a seismic vessel as a platform of opportunity. Nine cetacean sightings were recorded: pantropical spotted dolphin Stenella attenuata (N = 2), Fraser's dolphin Lagenodelphis hosei (N = 1), sperm whale Physeter macrocephalus (N = 1), humpback whale Megaptera novaeangliae (N = 1), and sightings of unidentified dolphins (N = 1) and large whales (N = 3). A total of 73.3 hours of acoustic monitoring effort was carried out during December 2007, resulting in 19 cetacean detections. Sperm whale (N = 10) and unidentified dolphin (N = 7) detections predominated. Two acoustic detections were of pantropical spotted dolphins, corresponding with visual sightings. An opportunistic sighting of 14 pygmy killer whales Feresa attenuata during October 2008 was reported. Although the humpback whale was known previously for Montserrat waters, the sightings of other species represent the first verified records for the state.