fire_diver
Contributor
Sorry, I don't believe that spent any time in saltwater. I have dug plenty of coins from the beaches, and I've never seen copper or copper alloy comes out that clean and crisp.
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Coin one is pretty clearly from the reign of Domitian (Domitian - Wikipedia, the free encyclopedia)
Coin two is from the time of Antonius Pius (Antoninus Pius - Wikipedia, the free encyclopedia)
Coin three is Gallenius (Gallienus - Wikipedia, the free encyclopedia)
Coin four is Constantine I (the DN at the beginning stands for Dominus Noster)
In other words: Your coins already cover several centuries - they cannot come from one wreck but are pretty clearly a coin collection. As fire diver said: They are in very good condition. I have personally digged out far worse examples - and they were younger, in earth instead of salt water and mild European climate. This is not some ancient treasure...
(I don't see anything on #2 to indicate a A. PIUS)