Stairs going up from overworld in Minicraft

I've come across stairs going up in the overworld that have barriers in the eight squares around them.

My Iron Pick can't break them. What do I need to find to be able to go up and explore?

Solution 1:

You will need a gem pick. Gems can be found in underground level 3. (Which is, by the way, full of lava).

Solution 2:

From this forum:

There are stairs going up and down scattered throughout the world. Access to stairs going up require pickaxes made of ore that can only be found underground. Be sure to bring a lantern.

Solution 3:

You need to get to underground LV3. To get there, find the downwards stairs from LV2, which is the downstairs area from LV1. Find Gems in LV3 (which is full of lava (-4hp)), make a pick out of those, then break through to the overworld. You will also need many, many lanterns, and enough gems to make a gem sword (so about 10 in total).