Agreed. There are mountains that don't survive getting crushed between two icebergs. If the sphere were made of solid tungsten, then okay, I'd buy it. Short of that, I have doubts.

The Titanic wasn't crushed, it was sliced, wasn't it?

Correct. The forces involved when icebergs move are vast. This thing will be crushed like a coke can. Even a deep-sea titanium sphere might not survive such an asymetric load as being crushed between a berg and a rock.