Which DSV was refitted to dive to a maximum depth of 10,000 FSW?

The DSV-3 Turtle underwent significant modifications to enhance its operational depth capabilities, allowing it to reach a maximum depth of 10,000 feet of seawater (FSW). This refitting involved upgrades to its structural integrity, buoyancy systems, and pressure equalization mechanisms, among other enhancements, making it suitable for deep-sea exploration and rescue missions. The Turtle's design and construction have been recognized for their innovative features that support deep dives, which is essential for missions that may involve responding to underwater emergencies or exploring deep-sea environments.

In contrast, while the other submersibles listed have their unique specifications and capabilities, they were not specifically refitted to achieve the depth of 10,000 FSW as the Turtle was. This clarification helps understand the advanced engineering and operational requirements necessary for such deep-sea missions.