Question for kids swimming on vacation?

I’m going on vacation and my 5 and four year old have been in swim I’m swim lesson but can’t 100% swim in assisted yet. Looking for suggestions on what is the best swimming aid to bring for them?

They used to use puddle jumpers but was thinking of bringing a swimming bubble belt. The resort we are going to has both pool and beach in the carribean

Looking for any suggestions or advice. Thank you in advance!