Mexican environmental authorities say they were able to lead seven beached dolphins back to sea but 16 others died on the beaches of the Baja California peninsula.
Mexico's environmental protection agency says 21 were rough-toothed dolphins and two were common dolphins.
The agency said Tuesday that the mass beaching occurred the previous day at San Lázaro Beach on the Pacific coast along 1.2 kilometers (0.75 miles) of beach.
It said local fishermen and coastal watch activists helped save seven of the dolphins, despite strong wind and waves.
Most of the others were buried near the beach, but three dead dolphins were taken to a local university for tests to see why the mass beaching occurred.
There was no immediate evidence of any entanglement in fishing gear.