some excursions have other age limits tho - like in Freeport for the dolphin swim you had to be 12 or older to participate.
For stateroom pricing, two people in the stateroom are full price regardless of age. After that there's under age 3 pricing, 3 to 12 pricing, and "all others" (meaning 13 and older) pricing for the 3rd, 4th, 5th passengers in the same stateroom.