A navy damage control team has boarded a burning ocean-going tug off Northland hours after the crew abandoned ship when fire broke out in the engine room.

The NZ Govt is putting pressure on Japan to participate in an investigation into the sinking of an anti-whaling vessel, John Key says.

A lack of Japanese co-operation has meant an Australian investigation into Ady Gill's collision with a whaling boat was 'inconclusive'.

Police are searching for a second man who is presumed drowned after a floundering expedition went tragically wrong.

The body of a middle-aged man without a lifejacket was found floating in Auckland's Waitemata Harbour yesterday, renewing safety calls.

Crowds are gathering at beaches to watch the tsunami threatening New Zealand, says the coastguard.

Rescue services were flat-out with 25 callouts by 5pm yesterday.

Figures released today showed 98 people drowned last year, the second lowest annual toll since records began in 1980.

One fisherman drowned and three others spent hours clinging to their boat after it capsized in the mouth of the Manukau Harbour.

Coastguard leaders say many boaties rescued by its volunteer crews refuse to pay the $280 an hour fee to cover the charity's costs.

A fisherman whose boat sank in the middle of the night was so determined not to surrender it that he swam the waterlogged vessel nearly 1km to safety.