Welcome aboard, Cedric! Checking out all of the wonderful Port Adventures that Disney Cruise Line has to offer is half of the fun of setting sail! There are plenty of Port Adventures that are perfect for the whole family, no matter their ages.
Age limits are specified on each adventure's listing, and they are strict on enforcing age limits. In fact, the booking system will not allow you to add your 11-month old to the reservation of a Port Adventure where her age is not within the limits.
The easiest way to sort which
Port Adventures are good for little ones is to first view the page listing the adventures for the specific port of call you'd like. Then, scroll down a bit and watch the left of the window where you'll see Age Range as a category. Check "0-2". This will limit the Port Adventures you see to only those that allow children that young. Some adventures do charge a fee for these young kids, but others may list the Infant Price as $0. Even better, right?
You're welcome to bring your own infant life vest for use on Port Adventures, but most water adventures for young kids will have those included. There are life vests for all sizes available for onboard use near the pools on the pool deck too, as well as at Castaway Cay. I don't know of a place where you can inflate your own on the ship, so you may simply choose to use the provided ones, or possibly bring your own that don't need inflation. Guests are not able to bring their own rafts for onboard use. Castaway Cay does offer raft and float rentals for a small fee, and you can simply walk up and rent that day if you decide to. There are plenty, so even if you don't book a raft or float ahead of time, there will be some available for sure that day.
Have fun planning your cruise, Cedric! You're in for one magical family vacation!