I have been to St. Vincent one time. It is a green, fertile, mountainous island that is basically undeveloped. It is approx. 18 miles x 11 miles--has a 3000 ft volcanic mountain and several waterfalls. The official language is English.
The main city is Kingstown where the ship will dock.
St. Vincent has a small population of Caribe Indians and was one of the last islands in the Caribbean to be colonized due to the fierceness of the Caribes.
We did an island tour through the ship and really enjoyed it. I would love to go back someday. The official website for St. Vincent and the Grenadines is---
www.svgtourism.com
Check it out. It may help.