Are the spoils on a sunken ship truly lost?

When a crew's ship is sunk, are any treasures on it completely lost? or is there ways to retrieve the riches on that boat?

For instance, if my boat was sunk right next to an island, could the treasures be retrieved on the seafloor?

Solution 1:

No, spoils on a sunken ship aren't immediately lost. When a ship sinks, any player loot on it will float to the surface of the water. After 5 minutes, floating player loot will sink. After 5 minutes on the sea floor, player loot will disappear.

Player loot lasts longer on dry land. Reports on the Sea of Thieves forums indicate that player loot on land lasts somewhere between 1-2 hours before disappearing.

Reference

• Treasure chest despawn
• Treasure Chest Mechanics?