The map above shows what Adam’s Bridge (aka Rama’s Bridge or Ram Setu) in the Palk Strait might have looked like prior to 1480 when it connected India and Sri Lanka.Here, you can explore it on Google maps:
In 1480 a cyclone supposedly deepened the channels between India and Sri Lanka, rendering it impassible by foot. However, today some sections are still only between 1 and 10 meters (3 and 30 feet deep) as can be seen in this photo from NASA’s Landsat 7 satellite:
Reminds me a lot of the shifting islands on the Eastern Shore. There used to be complete roads out there, too.