This one is no April Fool’s joke. A basalt-boulder structure, wider and taller than Stonehenge, sits under the water near the SW coast of the lake.
The structure was discovered in 2003 during a sonar survey. The structure consists of basalt boulders around 3 feet (1 meter) long. The entire structure has a diameter of around 230 feet (ca. 70 meters) and its central cone rises 32 feet (ca. 10 meters) from the structure’s bottom.
[The researchers] say it is definitely human-made and probably was built on land, only later to be covered by the Sea of Galilee as the water level rose.
The total weight of the structure is estimated at around 60,000 tons. For perspective, a fully-loaded Iowa-class battleship such as the USS New Jersey is roughly the same weight. That is *a lot* of stone for ancient people to transport and assemble. Very impressive.
For such an impressive monument, scholars don’t yet know what it is, who built it, or even when it was built. (It could be a cairn – a pile of stones to commemorate a burial.) They hope to undertake an underwater excavation to gain answers to these questions.
An article on the discovery is here. You can see a photo gallery of the discovery here.
HT: Joe Lauer
Bible, Archaeology, and Travel with Luke Chandler 
I remain skeptical and am waiting for further work to be done for me to make conclusions about this.
It seems like the ones who announced this are also hesitant to make conclusions. We have a stand-alone, 230-ft. diameter, circular pile of basalt stones on a (currently) underwater slope near the coast with a distinct conical feature roughly in the center. Beyond that, it’s technically anyone’s guess at this point.