Two identical sensor pods.
Somewhere from 50 m to 10,000 m, in 50 m steps, is the crush depth: a pod survives any dive shallower than it and implodes at or below it.
A surviving pod can be reused. An imploded pod is gone.
You know a pod implodes at 10,000 m.
What is the fewest dives that guarantees you find the crush depth?
If your first pod implodes, how many dives does the second need?
Happy birthday, Sam.