Variety in the types and amounts of treasure can often enhance the
enjoyment of Dungeons and Dragons. On the high seas, an encounter
with an alien merchant ship leads to a brisk battle, after which the victorious
party examines the cargo hold to determine their booty. This
captured treasure can turn out to be either highly valuable or next to
worthless. The following outline was developed for a voyage to Japan
which was never completed (although the characters involved passed
off Nubian slaves as captured Japanese peasants).

Cargo can only be determined after grappling and surrender or
annihilation of enemy forces. Small merchant ships can hold up to
twelve units of cargo, while large merchant ships can hold up to thirty
units. Roll a six-sided die for each kind of treasure possible; each roll of
a one means that there are from one to six units of that particular type
of cargo on board. If the total number of units of cargo is greater than
the capacity of the ship, neglect the least valuable cargo.
 

Cargo	Value per Unit Gold Pieces	Comments
Spice	-	-
Silk	1000	-
Precious Stones	1000	Amber, flint, jade, marble, emeralds, etc.
Ivory	-	-
Precious Wood	300	Only 1-4 units; ebony, teak, balsa, etc.
Tea	350	-
Cotton	250	-
Jewelry	1000	This is primitive and low-grade stuff, not the jewelry used in normal D&D campaigns.
Cloth	250	-
Livestock (exotic)	250	Camels, falcons, peacocks, monkeys, ocelots, Arabian horses, etc.
Fruits and vegetables	100	Spoilage may occur, especially over long voyages.
Foreign slaves	-	20-60 people

Also, roll for treasure — type A.
There is also a 15% chance that a few passengers are aboard ship.
These passengers can be merchants, adventurers, or noblemen.