Parked our car at Thunder Hole, which is about the mid point of Ocean Path Trail. Acadia only reopened two days ago on Jun 1st since the coronavirus outbreak. We saw maybe 2-3 other cars in the usually crowded packing lot.
Thunder Hole got its name from the thunder-like sounds made by waves hitting the rock caves. You need to visit during a specific time of a day to hear that (supposedly midway between low and high tide). Unfortunately we were not there at the right time.
Get the AllTrails app and download the offline map area for Mount Desert Island in Google Map before coming to Acadia. The cell reception is really bad on the island so it’s good to have the map and trail details available offline. Also, many trails in Acadia intersect with each other which makes it easy to get lost or get on the wrong trail.