Grave concerns this morning for a tramper missing in Mount Aspiring National Park.

The man was ill-equipped when he left his tramping group on Sunday night to navigate a dangerous gorge near the Wilkin River.

Search and Rescue's Phil Melkeyor says his chances of survival are diminishing.

"We will do everything we can to bring this to the best conclusion that it can be brought to."

Melkeyor says the search for the man will resume this morning.

"We will go again for a second look to see if anything has come up overnight. Probably do another aerial search."