Surprisingly, the Pelican Micro cases will tolerate quite a bit of depth. I've seen them make it to 100' intact and dry.
The smaller cases - like the 1010 - do the best:
The small cases have good support for the clear plastic face, and do quite well. The larger sizes, like the 1050, have enough unsupported clear plastic that the front "dishes" in pretty severely as depth increases. Eventually the distortion is enough that it breaks the seal at the edge.
We've used this for GPS fixes from depth. Just place your GPS unit in the box set to record waypoints, and send it up to the surface with a reel when you want a GPS fix.
All the best, James