I would treat that as a bug necessarily. Shell craters and the like under water are notorious problems for beach landings. I just wonder if one would be able to make these kind of "fortifications" beforehand.
Can you place wire and dragons teeth in shallow water? It might be a case of "if one, then all."
Dragons Teeth and mines for sure. In fact you can do dragons teeth in deep water. Wire - Not as I recall.
Dragons teeth and mines make some sort of sense. I agree with yor shell hole comment and definitely for wading vehicles but it doesn't make sense for amphibs to get stuck in them.
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