unsubmersible

adjective2

1. •
   Not submersible.

   • The car will be prepared for all emergencies by making it unsubmersible and furnishing it with runners for use as a sledge. — 1890
2. •
   Buoyant and resilient; unquashable.

   • "He is unsubmersible." And he adds: "He believes in his wife, his belief is unshakable." — 1980