Puddle Jumpers are Coast Guard approved, so you are allowed to bring it. We brought ours for our hotel stay but never used it on the ship or Castaway. We were happy with the ones DCL provides.
You can use any "coast guard approved" life vest. It is listed under the okay but with provisions section in the faq copied below, bullet #3,
The following items are permitted but with the following restrictions:
Walkie-talkies and two-way radios (e.g., Motorola, JVC). Please be aware that the amount of steel in the ship's infrastructure may cause some "dead zones" and the radios may not transmit in these areas.
A small portable fan. However, please contact Guest Services to have the Chief Electrician approve the use of your particular appliance in the stateroom.
Coast Guard approved personal flotation devices (PFDs) and flotation sewn into the bathing suit for safety. However, recreational floating devices such as floats, rafts and fun noodles cannot be brought on board and are not permitted in the pools or on Castaway Cay.
Golf clubs, as long as they are stored in your stateroom.
I know puddle jumpers are coast guard approved...that's the main reason we bought it in the first place. my son is very comfortable in his puddle jumper...he's never used a life jacket. I just wanted clarification since Disney does provide life jackets, if we were allowed to bring out own. Now room in the luggage might be determining factor!
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