ADM Exploration Foundation - Phantom Cave 2013 READ MORE PLUS a 15 Minute Video Documentary by Becky Kagan Schott
As they descended to 400 ffw in depth, they noticed more chert nodules jutting from the walls, similar to the abundant amounts seen in the shallow section between 20 and 30 ffw but strangely absent between. A prominent dark formation protruded from the silt floor, possibly either a complex piece of chert or a fossilized coral. While Andy tied off to this ideal point, Brett looked ahead into the ongoing passage. As far as his light could penetrate, the cave appeared to continue at the same depth (462 ffw) as the floor of the large room. However, at this depth they could not continue exploration within their planned safety envelope; they very reluctantly turned and began their long ascent. They completed five hours of decompression and scootered out of the cave, emerging into a cold but beautiful starry night after a total dive time of 7 hours. Their maximum depth was 462 ffw, establishing Phantom Springs Cave as the deepest underwater cave in the USA.