D-Series RaftsThe AIRE D Series Whitewater Rafts are surprisingly agile, yet incredibly versatile boats that can accommodate anything from a paddle team run down the local river to a multi day whitewater expedition. The 'D' stands for diminishing tubes; in the bow and stern, the tubes diminish in diameter. This smaller diameter gives more rocker to the boats, lifting it up and over waves and hydraulics while also opening up more cargo space in the ends of the boat.