511 feet is approximately 155.76 meters.
511
The biggest recorded sinkhole is the Xiaozhai Tiankeng in China, which measures 662 meters (2,172 feet) wide, 511 meters (1,677 feet) long, and 320 meters (1,050 feet) deep. It is also known as the Xiaozhai Heavenly Pit.
4,421 meters is 14,504.6 feet.
600 feet = 182.88 meters.
138 meters = 452.755906 feet.
118 meters = 387.139108 feet.
239 meters = 784.120735 feet.
1.83 meters = 6.00393701 feet.
4,370 feet = ~1,332 meters.
624 meters=2,047.24409 feet
9,980 feet=3,041.904 meters