Test Baker — a U.S. nuclear weapons test conducted in the on July 25, 1946 — was notable for what reason?

The Quiz: Test Baker — a U.S. nuclear weapons test conducted in the on July 25, 1946 — was notable for what reason?

First underwater nuclear test
First nuclear test that failed to detonate
First nuclear test conducted jointly with France
First test in the Atlantic Ocean
First nuclear test in space

The correct answer to this quiz is First underwater nuclear test.