I want to be a scuba diving instructor but i also want to travel. I believe instructing in scuba diving involves traveling too.

If you’re a good candidate (physically and ASVAB qualified), you can request a certain career field and get it guaranteed on your contract. However, certain jobs are overmanned and/or aren’t in high demand. Those sorts of ratings will be harder to get into.

Right now, it’s difficult for many people to get the rating they want without lengthy wait times.