This happens all the time. I never considered it anything to note or contemplate. You don't have to go out to the middle of the Pacific.
In perfect weather, visible distance (D in NM) for an observer 8 feet above the water, looking at and object X feet high is:
D = 1.17 * sqr(X)
For example: a two story building is 20ft high, and possibly visible at 5.2 miles. Molasses Reef is about 7 miles from Key Largo. You would need an object on shore of 35 feet to spot it.
In practical terms, haze can obscure the horizon and any land at much closer distances.
been a long time since I have seen this formula. I use it a lot however.