Iron armor can't keep up with the mountains. Start hunting silver nodes, it's very satisfying to dig under and make them crumble all at once. A single boat ride will have more than enough for 2 players to gear out.

One of the benefits of digging deep is to trap golems. There is a spawn limit so if the golem is stuck, no more will spawn around.

Bonemass power is the get out of jail free card. When things look dire, pop the skill and power through.