[gene91]

Not sure whether it’s applicable here. But when learning scuba diving, we were taught (or rather reminded of, from middle school physics) that a balloon would become bigger as one gets closer to the surface. A balloon 90m under water will be 10X the size when it’s at surface. Therefore, using a balloon for emergency surfacing will lead to a monotonically increasing acceleration rate (which means you’ll going be too fast), or probably bursting the balloon half way through.

[mpreda]

Indeed the pressure is huge down there, and this may represent a challange in inflating the ballon in the first place. Looking up the numbers, it seems the pressure at the Titanic is about 400bar, while the pressure of a CO2 cartdrige is about 800bar, so that works.

About the baloon becoming larger as it surfaces, a pressure release valve that vents the baloon based on the pressure differential with the exterior (water) may do the trick.

[rasz]

Use a bell shaped contraption instead of a balloon.