Two people have been rescued after floating off on a “small inflatable mattress” on Lake Rotorua.

In a press release, Coastguard Rotorua Lakes said the pair were among four rescued from the water on Wednesday.

The day “turned into a nerve-racking situation” when four people last seen swimming did not return as expected, the Coastguard release said.

“[They were] possibly headed towards Mokoia Island, about 3.2km from where they started.”

Coastguard Rotorua Lakes was called in at 6.25pm.

Within half an hour, two rescue vessels, Lakes Rescue and Rotorua Rescue, had full crews and were out on the water.

“At 6.52pm volunteers on board Lakes Rescue spotted two individuals about 0.3 nautical miles (about 500m) offshore. They were brought on board and assessed for any injuries before returning to Hannahs Bay.”

The rescue vessels searched the shoreline between Hannahs Bay and Mokoia Island for the remaining two missing people before heading to Mokoia Island.

“At 7.44pm Coastguard located them on the island, having floated there on a small inflatable mattress.”

Two Coastguard Rotorua Lakes crews helped find and rescue four swimmers from Lake Rotorua on Wednesday.

There was an emotional reunion at Hannahs Bay when the two groups were reconnected.

Coastguard Rotorua Lakes instructor and master on board Rotorua Rescue Jonathan Findon said volunteers and staff had been “training extensively” in the lead-up to summer.

“Many of our training scenarios include situations similar to this operation, which allowed the crews to quickly put training into action,” Findon said in the release.

“Our crew came away from their evening with families to selflessly help people in need, and ended up with a fantastic result.

“I’m so proud of everyone’s efforts.”