An interesting day trip involves flying to Union Island in the Grenadines, then taking a sailboat or catamaran thru the Grenadines to snorkeling spots. It is a spectacular remote getaway.

How much would this cost ?

Depends on where you're coming from, but I've seen similar daytrips from barbados and St. Lucia and they were around US $250 per person, including everything except a tip.

EJ, is right. Most of the expense will come from air time. The boat trips are not that expensive and include lunch. We stayed a few nights on Union just to be able to do several day trips. Fantastic! If you are interested, click on my name and you should be able to find my trip report. Good luck. Owa

Thanks for the reply, we will be coming from Barbados.

This was about 6 years ago, but I took a day trip from Barbados to the Grenadines. It was around $250 per person, and worth every penny.
It included a small plane ride to Union Island, then Catamaran. We stoped at Petit St. Vincent, Mopion (one of my favorite little spots in Caribbean-basically a sand bar with decent snorkeling, incredible views, and one lonely umbrella) we were suppose to go to Tobago Cays, but squalls came in, so we ended up at Palm Island. It was an adventure!
It was actually the highlight of my trip to Barbados!

We did this trip from St Lucia and it was wonderful. We sailed with Captain Yannis. If the cost isn't too much of an issue, I would definitely recommend it. The scenery is spectacular.