The spa and gym are usually restricted to those that are 16 yrs old and older. Reason being is that conventional wisdom states that those younger really do not benifit all that much from this type activity but could harm themselves if not done properly. The cruiseline wants to be helpful and accessable but also must be concerned with potential libilities as well. As you are 17 there is no problem and your sister may not be bothered either as she is close and so long as it isn't an obvious problem with behaviour they most likily will not say anything.
Community Staff Leader