UPDATED 12.30pm: Poor conditions and lack of skills have combined to cause a near-tragedy off the Coromandel coast.

Two men ended up in the water when their boat flipped near Waihi last night, as they were trying to cross a bar.

One of them managed to swim to shore but his mate was in the water for seven hours, clinging to a petrol tank to stay afloat.

Waihi Beach Coastguard skipper Tim Watts said both men are lucky to be alive.

"The conditions were not ideal for what they were doing, and their skill level on crossing the bar was obviously not up to scratch."

Neither of the men was wearing a lifejacket.