Search for missing Maruia Falls swimmer likely to be scaled back amid 'extremely challenging winter conditions'

The swimmer has been missing since about midday yesterday. Photo / File

The search for a missing swimmer at a South Island waterfall has finished for the day, and efforts are likely to be scaled back tomorrow.

The swimmer has been missing since about midday yesterday after one other person was pulled from the water at Maruia Falls in Shenandoah, near Murchison.

Nelson Bays Area Commander Inspector Matt Scoles said this evening the missing person was unable to be located after a second day of searching.

The police National Dive Squad has now completed a thorough search of the area including the falls, the pool of water between the falls and the river's edge, and the river itself.

The search will continue tomorrow but would likely be scaled back in terms of the number of people involved, Scoles said.

"These were extremely challenging winter conditions for dive squad staff and other search personnel, including the Nelson Bays Search and Rescue staff, local Nelson surf life saving crews and local river experts, to work in."

Scoles said staff were constantly reassessing the information and the conditions to help determine the next phases of the search operation.

"As the public can appreciate this is a very hard time for the family and we are doing all we can to support them."

Scoles said police remained in regular contact with the family and were providing all necessary support.

"Our deepest sympathies are with them during this tragic time."

Police also thanked those who have been assisting in the search.