The reason you might have been offered so much of the spiky, strong-smelling fruit known as durian while enjoying the Teuk Chheu rapids is because of the proximity of the plantations, which line either side of the road en route.
Kampot durian is famous throughout Cambodia for its flavor and sweetness. It is deemed superior to Thai durian by Khmer connoisseurs (Prime Minister Hun Sen among them) and the price reflects this it can cost twice as much as its imported counterpart. Many foreigners do not enjoy the strong taste and smell of this strange fruit, with its creamy yellow flesh encased in brown spiked skin, but those who do will find the cheapest (and tastiest) durian in the Kingdom in Kampot.