While at the beach today, I made an amazing discovery. The earth is round! It was such a clear day, I could see Block Island quite well. It's about 12 miles away, and given that distance the curve of the earth appears to be visible. Take a look at this cropped image:
The building in the center is Block Island North Lighthouse. Notice how it appears to be right on the sea level. Now look at this picture take from a much closer distance (image linked from the Block Island tourism web page):
Or for an even better view, look at this. The lighthouse is obviously on a small hill. But, with my 12 mile away view, it appears at sea level as the hill is hidden behind the curvature of the earth. There are other parts of my cropped photo showing just the roofs of houses on the island viewable behind the edge of the sea, but I thought it was interesting to compare this recognizable building with photos taken from the island to get a different perspective.
And yes, I do realize everyone really already knows the earth is round. But it's still kind of neat to be able to see it first hand.