Jordi Nin was visiting Remarkable Cave, south of Port Arthur on Saturday, when the wave hit.
"I was down there probably two minutes before and got completely drenched,'' Mr Nin said.
"Luckily I saw the wave coming and got my camera under my jacket to protect it.''
The Stewart Bay Lodge manager said viewers on the walkway, got about five seconds warning before the cave filled with water.
The walkway was closed several hours later and Mr Nin said part of it had since broken free and washed away.
After experiencing the wave first-hand Mr Nin said he had gone back to the top to get the event on video.
"The waves were doing that for some time so I just waited and got one on camera,'' he said.
"According to the locals it does get like that, not often, but when we had that storm four or five months ago with the huge waves at Shipstern's [Bluff] it got quite big too.''
Remarkable Cave, about 2km south of Port Arthur on the Tasman Peninsula, is normally accessible from the beach.
Source: The Mercury