The mysteries of underwater life have long been a source of inspiration for writers, filmmakers, and marine biologists. But scientists interested in understanding the biological diversity of the oceans are often limited by the relatively shallow depths accessible via scuba diving. Small research submersibles, while expensive, allow for the exploration of much deeper waters. A new paper co-authored by researchers at the Smithsonian's Tropical Research Institute (STRI) and National Museum of Natural History (NMNH), the University of Washington and the Universidad Nacional Autónoma de Honduras describes the important contribution of submersibles to increasing our knowledge about the diversity of deep-reef fishes in the Greater Caribbean.