The deadliest weapons platform in SH4 is.....

[seafarer]

A PBY-5A (the most numerous version built) Catalina's bomb load (2 hard points per wing) could consist of:

4 × 1,000 lb or 500 lb bombs, or
12 × 100 lb bombs, or
4 × 650 lb, 450 lb, or 325 lb depth charges, or
2 × 2,167 lb Mk 13-2 torpedoes

Don't know what the game loads them up with.

An A6M2 Zero could carry up to two bombs of up to 132 lbs each