A hypothermic capsized kayaker had spent an hour in the water by the time they and a companion were rescued from the Firth of Thames.

The pair were off Tapu when they got into difficulty as darkness approached on Monday, with Coastguard Thames volunteers receiving an alert about 7.20pm.

Coastguard responded with six volunteers onboard the Richardsons Rescue vessel, says a statement.

Coastguard Thames skipper Steve Mansell says finding the kayakers was no simple task, with fading light and an increasing offshore breeze.

'The target was initially reported as 500m off Tapu, which turned out to be 2NM off the coast.

'We were very lucky to pick them up, we did an initial search in the reported location when one of our volunteers spotted something in the far distance, which we investigated and located the two kayakers at around 8.20pm.”

Coastguard stayed in contact with the two kayakers until Richardsons Rescue arrived at the scene.

The kayakers had been wearing life-jackets but needed urgent medical attention for hypothermia, says the volunteers.

'It was critical to assess their vitals and start to warm them up as soon as we got them aboard. We have crew with EMT experience on-board which is invaluable during incidents of this nature,” says Mansell.

They were transferred to hospital by ambulance and later discharged.

'We had an incredible response to the incident last night – with more volunteers than required responding to our pager. We're grateful this incident had a positive outcome.”

-Te Aorewa Rolleston/Stuff.