The Titan had multiple failsafes to drop ballast and return to the surface under its own buoyancy. One such failsafe was time-delayed by material corrosion in s

The Titan had multiple failsafes to drop ballast and return to the surface under its own buoyancy. One such failsafe was time-delayed by material corrosion in seawater so it would eventually ascend without intervention. The cabin electronics weren't essential to its safety. The hull might have been, though. Hard to say.