The diagram is missing, so i have attached it.
Answer:
-1000 ft
Step-by-step explanation:
From the diagram attached, we see that they went 1000 ft below the sea level.
Now an altimeter is used to measure altitude depth of an object relative to a fixed level which in this case the fixed level is the top of sea. Since the depth in this case is below sea level, it will be negative.
Thus,the altimeter will read -1000 ft
