It plays host to superyachts and celebrities but the latest international visitor to Auckland’s Viaduct Harbour has snuck in under the radar - and prompted a warning from authorities.

A banded sea krait - a highly venomous sea snake from the Pacific - was spotted at the popular marina this morning by the crew of the Peretū.

The boat, which offers cruises around the Hauraki Gulf for the Explore Group, was about to leave this morning when the interloper was spotted curling through the still water.

A spokesperson for the Explore Group said it was the first time the crew had spotted a sea snake and the sighting was quickly reported to the Department of Conservation.

Clinton Duffy, Technical Adviser Marine at DOC, told the Herald that banded sea kraits were “rare stragglers” to these islands but were considered a native species under the Wildlife Act 1953 because they arrive here naturally on ocean currents.

Banded sea kraits can be found in the water - and on land. Photo / Supplied

The animals are also offered protection under the act, meaning that it is illegal to kill or harass a sea snake, or possess one or any part of one without a permit.

Duffy warned that sea snakes and kraits are highly venomous but said they are “docile creatures”.

 “Nevertheless, if you find a sea snake or krait keep well away and call 0800 DOC HOT,” he said.

The sighting is the latest in a series of appearances of venomous snakes in our waters, coming after a rash of sightings of the yellow-bellied sea snake last year.

That animal, which breeds in the tropical waters of the northern Tasman Sea, has been seen as far south as the Manawatū coastline, where a man was prosecuted last year for taking one from a beach.

But crucially it is a solely ocean-going species.

This is not the case for the banded krait.

This venomous visitor is a coastal creature and often comes ashore to rest and to regulate its temperature, Duffy told the Herald.

“Water temperature will influence how long they survive in New Zealand waters. At temperatures below 18-20°C survival time is progressively reduced, feeding ceases first, then swimming and diving, and eventually they lose the ability to orient themselves,” he explained, before noting somewhat ominously that “the video suggests the snake is not suffering any of those symptoms”.

A staff member at Explore Group told the Herald that she did not feel unsafe but was “keeping her distance” from the water this morning.

Good plan.