Hoover Dam Aggregate Plant (Lake Mead)

The submerged remains of the aggregate washing and classification plant that processed more than 6.5 million tons of sand and gravel for Hoover Dam's concrete, flooded when Lake Mead filled. The site spreads over roughly 8 acres of Boulder Basin and includes train tracks, a track hopper, tunnels, underground rooms and massive sorted aggregate piles. Local operators dive it as two separate sites (the Track Hopper and the Aggregate Piles) at about 70-100 ft, normally by boat charter; winter visibility can exceed 100 ft.