If a submarine was under a thick ice cap and really needed a hole punched in the ice above, could it fire a torpedo to do the trick? How thick of ice can a submarine handle?
How thick? This page indicates that ice thickness is less than 3 metres, but that’s around Canada; this article indicates that we don’t really know how deep the ice is. I don’t know if even the 300 kg in a Spearfish torpedo could break through 3 metres of ice: ice is pretty tough.
Of course, a torpedo with a nuclear warhead should do the job easily.
Fortunately casdave and robby should be along shortly.
<channeling mraru>
You can fire a torpedo at an ice cap from underneath … if you want to kill yourself [hydrostatic shock is a bitch]
The current break record for 18 feet of icepack is held by the San Juan SSN 751, however whenever a sub is under ice, it tracks the location of polyanas [areas where the icepack has melted for one reason or another] so the breakthrough points are known.