A man was arrested last night after a two-hour manhunt in the Marlborough Sounds involving maritime police from Wellington and the armed offenders squad.

The hunt began after a Nelson man told police he had been assaulted, stabbed and thrown overboard from a yacht in the Queen Charlotte Sound on Tuesday night.

Sergeant Kris Payne said the man told them he had been visiting Picton and met a man who invited him on to his yacht.

At some stage the man had been thrown overboard and had swum to the nearest shore, where he spent the night in some bushes.

He had walked to Lochmara Lodge, in Lochmara Bay, yesterday morning.

The bay is on the opposite side of Queen Charlotte Sound to Picton harbour.

He told police he had been assaulted and attacked with a knife and a wood saw.

He had a deep cut to his hand, which had been patched up but he would have it checked at Wairau Hospital, in Blenheim, today.

He also had cuts on his body and face, Mr Payne said.

Police arrived at Lochmara Lodge yesterday afternoon and brought the man back to Picton.

As they were leaving the bay, the man spotted the yacht he had been on tied up at a jetty.

A police maritime unit called in from Wellington arrived in Queen Charlotte Sound on board the Lady Elizabeth IV late yesterday afternoon and met up with the armed offenders squad, Mr Payne said.

A customer at a cafe on the waterfront said about five officers dressed in armed offender clothing, including a dog handler, boarded the police launch in the Picton marina about 5.30pm.

The 18.5-metre police catamaran left the harbour and was seen going to Double Cove, just north of Lochmara Bay.

The catamaran returned to Picton marina just before 7pm and several more police officers, some carrying large bags and guns, boarded before the boat headed back out the sound.

Tasman District police spokeswoman Barbara Dunn said a 53-year-old man had been arrested and taken into custody about 8pm.

The police launch arrived back in Picton harbour about 8.40pm and the arrested man was put into a police car.

The man will appear in Blenheim District Court today on charges of wounding with intent to cause grievous bodily harm and threatening to kill.

- © Fairfax NZ News