Currency in the Virgin Islands

Hi, booked a cruise for St. Thomas and St. Martin. Can anyone tell me what the currency is for each island? Also, if not US currency where is a good place to exchange some green backs?

Thanks for the replies. :)

Good old US greenbacks accepted everywhere. St Thomas is US territory. French side of St Martin uses the Euro, but most places will take US$

That's great to hear thanks!

Someone failed geography.