Shipwrecks can generate in the void
If you use the floating islands world type and set it to beach, it causes shipwrecks to generate partially in the void, causing them to get cut off. As a result the sometimes do not have chests.
Example
-9208981173496188401 @ 90, 0, -720
2021-06-09, 02:51 AM
2021-06-12, 03:27 PM
2021-06-12, 03:27 PM
0
2
-