Complex sentence: Because the ship had sunk in such deep water, the Key West wreckers were unable to salvage all the cargo, but the cargo they did salvage had a payoff of over $50,000 making the Isaac Allerton the richest wreck in Key West history.
Split into simpler sentences: Because the ship had sunk in such deep water, the Key West wreckers were unable to salvage all the cargo. But the cargo they did salvage resulted in a payoff of over $50,000 making the Isaac Allerton the richest wreck in Key West history.