Sea cucumbers (phylum Echinodermata) are common members of benthic communities in many marine ecosystems. They function as nutrient recyclers and bioturbators of soft bottoms, and are preyed upon by birds, fishes, mollusks, crustaceans and other taxa. In the Central Mexican Pacific, Islas Marietas harbours a complex and diverse community of corals and benthic invertebrates, with a particularly well-represented assemblage of echinoderms. However, little is known about the diversity of holothurians in the area. Between 2012 and 2014 a bimonthly census was conducted at Islas Marietas, and seven species were recorded for the first time at this location: Holothuria (Halodeima) inornata, Holothuria (Mertensiothuria) hilla, Holothuria (Platyperona) difficilis, Neocucumis veleronis, Lissothuria ornata, Afrocucumis ovulum and Pachythyone pseudolugubris. The absence of previous records of these species may be associated with their low densities and cryptic habits. This report acts to fill a critical knowledge gap in the distribution of holothurians in the eastern tropical Pacific and highlights the under-appreciated biodiversity of this Natural Protected Area.