Choc-ice can be bought from a local vendor named Rokuh in Nardah. They are sold for 30 coins each. When eaten, they heal 6 hitpoints, and quench a player's thirst if they are in the desert. This can come in handy as an alternative to bringing waterskins to the desert. Although waterskins are refillable and have up to 4 uses each, Choc-ice has the advantages of being weightless and dual purposing as food. This can be particularly useful for doing the Agility Pyramid.
Choc-ices were developed to aid the people of Nardah. When the town was cursed and could no longer provide water, a man bought a box of magical non-melting ice. He used this to help keep the people of the dying town hydrated. Despite this, choc-ice can melt when in the Kharidian Desert. Perhaps the ice can only melt while outside of the box.