The seal came ashore two weeks ago at Dolphin Cove near Merimbula and is only the fourth of its kind to be recorded on the NSW coast.

The visitor first was thought to be a leopard seal but photos revealed it to be a species rarely found outside Antarctic waters.

"We had one of the country's foremost authorities on seals take a closer look and it turns out this was in fact a crabeater seal, something we would not expect to find on a NSW beach," NPWS spokesman Geoff Ross said.

"What it was doing here, we don't know. It certainly didn't look to be in trouble."

The crabeater seal seems misnamed. It eats krill, small fish and squid but not crabs.

Distinctive characteristics include a dog-like face and brown spotted fur. But the appealing appearance could be misleading.

Stay well away from seals resting on shore, Mr Ross advised, because they could become dangerous when disturbed or startled.

The sighting follows a visit from an injured leopard seal which was found near the Bellambi boat ramp last month.

The seal was suffering a head injury believed caused by a cookiecutter shark.