Yup. The ice age. When the ice age ended, the water level rose on the coasts a lot. 50 feet? 100 feet? 150 feet?
People live on the coasts now. All the ice age coasts are now underwater. There is likely a lot more undiscovered stuff underwater.
the water level rose on the coasts a lot. 50 feet? 100 feet? 150 feet?
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400-700 feet