A scuba diver starts at sea level and then dives below sea level by 42 feet. The diver then ascends 18 feet and follows that by descending 7 feet. What is the diver's current depth?
67 feet below sea level
67 feet above sea level
53 feet below sea level
31 feet below sea level
The scuba diver started at sea level and then dived below sea level by 42 feet, so the current depth is 0 - 42 = <<0-42=-42>>-42 feet.
The diver then ascended 18 feet, so the depth is -42 + 18 = -24 feet.
Finally, the diver descended 7 feet, so the current depth is -24 - 7 = -31 feet.
Therefore, the diver's current depth is 31 feet below sea level. Answer: \boxed{31\text{ feet below sea level}}.