The term 'relaxing' takes on a different meaning when you have someone to run after.
So far my DS has been to North Qld, Melbourne, an NT holiday and many many trips to Sydney.
It won't be like you were used to when it was just the two of you. TBH it took DH and I a while to get used to that. Him because I expected the duties to be shared and me because he didn't expect to have to share any duties. Lay out some ground rules between you two so you both know what to expect when it comes to both getting time out, be it together or individually.
Remember a little person can't always 'go with the flow' so any holiday brings some unsettledness from bub.
Get her used to the water before your trip so you don't spend the whole holdiay stressing if she hates it.

ummm that's all I can think of ATM.