2.17. Two men are found dead outside of an igloo. (SK

2.17 answer: The men have gone spelunking and have taken an Igloo brand
cooler with them so they can have a picnic down in the caves. They cleverly
used dry ice to keep their beer cold, not realizing that as the dry ice
sublimed (went from solid state to vapor state) it would push the lighter
oxygen out of the cave and they would suffocate.