> How old is the oldest Corvette?

If you're talking about the ship, the oldest was built in 1859 by the British Royal Navy. The first Chevrolet Corvette sports car was built in 1953.

> How many times does the International Date Line cross the 180th meridian?

It lies on the 180th meridian for a long time. If by cross you mean intersect it along a straight path, then it only does that once. However, it also approaches the 180th meridian, runs along it for some distance, and then goes off in the other direction. If you count that as crossing, then it's twice.

> How much of Okeefenokee Swamp is in Florida?

Not much at all. Given that the whole swamp is about 400,000 acres, judging from maps I'd say about 10,000 acres of it are in Florida.

> What is the name of the river that empties into the Atlantic at Jacksonville, Florida?

St. John's River.

kniv"The Okefenokee one was a long shot"etsil