Actually, the problem with Truk (and every other Atoll) is the lack of a REEF. Truk Lagoon had no "port" even as big as the smallest SH4 port object. It was an anchorage. There were only a few gaps in the reef, and they were not all that much wider than a couple of ship beam widths or maybe ship lengths. Getting inside Truk Lagoon should basically be impossible.

The only possible ways in for a sub, even on the sirface are marked on that pic as a "pass."
We really need "reef" objects.
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