Oracle Text

Cumulative upkeep U (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)

Whenever an Island is tapped for mana, its controller may add an additional U. If that Island is snow, its controller may add an additional UU instead. Spend this mana only to pay cumulative upkeep costs.

Card Rulings

8/1/2008 This mana is in addition to any mana the Island itself produces, and is blue regardless of what type of mana the Island produces.