Check out this picture of the U.S. Navy's P-8 subhunter launching a torpedo for the very first time. As you can see, the Mk 54 test torpedo was launched on Oct. 13 from the 737-based jet's weapons bay (notice how the bay doors are open in the photo).
The test drop happened at about 500-feet above the water and was the first in a series of P-8 weapons tests meant to evaluate safe separation from the aircraft, delivery accuracy and weapon integration, according to NAVAIR.
It should be noted, that in addition to launching sonobouys and scanning the sea-surface with its APY-10 radar, the P-8 can also carry Harpoon anti-ship missiles and maybe even air-to-air missiles. (Its predecessor, the P-3 has carried, and used, Harpoon missiles, maverick air-to-ground missiles and Sidewinder air-to-air missiles.)
Click here to read about Boeing's pitch to make a modified P-8 into a giant, manned version of a hunter killer UAV.