By looking at the "Bing" (MSN) map of the area, it looks like they dug up half of the peninsula so that everyone could have waterfront property!
From an account by the interpreter Sampson, the store and camp was attacked the third night after the 2nd Dragoons arrived. The interpreters, and people from the store were going to cross the river to see an Indian dance, but were warned to stay away by the younger Seminoles. The next morning at daybreak was the attack. The prisoners were later cruely put to death, but it is believed that a cleck might have later escaped.
More importantly...This account says that the Colt rifles were left on the ground after the locks were removed, because they were useless to the Seminoles, but they weren't totally useless, as the soldiers would have had ammunition, and percussion caps, and I doubt that they were all just abandoned.
The Seminoles returned to the south bank of the river, and remained intoxicated for three days. The silver coins was alledgedly taken by one man, and later "sold" to other Indians, and beat into ornaments.
I would think that three days of drinking, and not caring much for the rifles, and coins, might would make the other side of the river worth looking into.
Also...It appears that the location is in a park....If that is a STATE park....I would be very wary of taking a metal detector into it!