A submersible expert who testified at the Coast Guard's hearing on the catastrophic 2023 implosion of OceanGate's Titan submersible Tuesday recounted a harrowing 2019 experience he had aboard the first prototype of the sub. Karl Stanley, who owns a deep-sea diving expedition company, said he went down to about the depth of the Titanic wreckage with three others, including OceanGate co-founder and CEO Stockton Rush, who was one of the five people killed in last year's disaster. He said Rush had warned the group about cracking sounds in advance, but when they heard them on the dive, it was disturbing. "I think nobody wanted to be the one to say they wanted to go up first," Stanley said. They returned to the surface without incident, but a crack was found in the hull a month later, ABC News reports. More from Tuesday's testimony: