Scott C. Waring, editor of ufosightingsdaily.com, made the claims based on a "shadow in the water" off the coast of Cape Town, South Africa.
Writing on his website, he says: "The shadow resembled an airliner."
The Malaysia Airlines plane disappeared in March 2014, killing 239 people who were en route from Kuala Lumpur to Beijing.
In his post, Waring appears to suggest that the Boeing 777 survived the crash in one piece.
"The Google Earth photo is dated 27/6/2015, and it crashed on 8/3/2014,' he writes.
"It's had 16 months of moving about."
He adds: "The Cape of Good Hope is going to have powerful currents moving around it with deep crevices, and since the photo on Google is eight months old, it could have moved 30-60km away if its semi-floating only 4-9 feet under the water."
"I know there is less than one per cent of one per cent of a chance that this is MH370, but it's better than we had five minutes ago right?"
Waring's theory follows an announcement from Malaysia's transport minister, stating that there was a "high possibility debris found in Mozambique belongs to a B777".