Two Cape Cod beaches were temporarily closed to swimming after shark sightings Sunday morning, according to the Atlantic White Shark Conservancy, while false alarms caused concerns at other area beaches.

Nauset Beach in Orleans was temporarily closed for an hour after a great white shark was sighted just 15 yards out in front of the northern lifeguard stand, according to the conservancy’s Sharktivity app, which confirmed the sighting. It marked the first such sighting of the weekend cited on the app.

About an hour later, Coast Guard Beach in Eastham was also closed to swimmers for an hour after spotter planes caught sight of a shark nearby, according to the app. The beach was expected to reopen at about noon.


Two beaches on the state’s North and South shores also briefly closed to swimmers Sunday morning after false alarms.

The water at Crane Beach in Ipswich was also closed in the late morning due to a report of a possible fin sighting, but it was reopened at about noon when nothing further was observed by boat or drone, according to the Trustees, the organization that oversees the beach, on Twitter.

For the second day in a row, Duxbury Beach ordered swimmers out of the water due to fin sightings that were later confirmed to be sunfish, Duxbury police beach operations said on Twitter.

Ocean sunfish, harmless sea creatures that can weigh more than a ton, sometimes float near the surface with a fin in the air, resulting in a number of local false-shark sightings in recent years.

Lucas Phillips can be reached at lucas.phillips@globe.com.