There are several significant disparities among these activities. Skin divers use the same equipment as snorkelers, but instead of staying on the surface, they dive below to get a closer look at the marine life. Freediving is a sport in which competitors attempt to dive as deep as possible without taking a breath. Freedivers often use a mask and long fins, although snorkels are avoided due to the drag they produce. SCUBA divers have air tanks strapped to their backs so they can breathe underwater.