The main types of goods bartered (making up the backbone of the Hawaiian economy of the time) were fish and agricultural products such as poi and sweet potatoes.
In old Hawaii, land was divided up into ahupua'a, which were typically river valleys stretching from the mountains to the sea. Within each of these ahupua'a would typically exist the resources needed for ancient Hawaiian life. However, they would not all exist in one place. Therefore, barter was needed.
The typical barter system involved fishermen (who of course lived at the shore) bartering fish with farmers who lived farther inland. The farmers grew taro (which can be made into poi) and sweet potatoes. The two groups traded these goods with one another.