Elephant Butte Reservoir

New Mexico's largest-capacity reservoir on the Rio Grande, named for the volcanic core island near the dam, with maximum depths over 150 feet. It was historically a regional dive destination — divers explore volcanic rock around the butte from shore or rented boats — but years of low water have stirred fine sediment so that visibility is now often only ~3 feet, dropping to near zero below 30 feet. It remains open to diving but is generally regarded as a poor-visibility novelty dive today.