Just a bit over three miles east of Key Biscayne, near Miami, Neptune Memorial Reef features a man-made, imagined replica of the Lost City. The series of pyramids, towers, and sculptures is spread out across 16 acres of the ocean floor, 40 feet beneath the surface. The structures were designed to promote coral growth, but here, the reefs aren’t the main attraction—Neptune Memorial Reef is an underwater cemetery. Many of the divers here are visiting recently deceased loved ones. Those who choose to be buried at Neptune are first cremated, and then their remains are “carefully mixed with non-porous cement, sand, and water,” according to the organization’s website. Finally, that mixture is poured into a mold of the person’s choice (conch shells and starfish are two options), and a bronze plaque bearing their name and life dates are attached. For now, there are 200 plots, but plans are underway to accommodate as many as 125,000 watery graves. The company recommends eight local operators, which lead diving trips to Neptune. For now, you can tide yourself over with a video tour.