If you mean us (the Dominican Republic) the first half of March is usually the end of the whale-watching season in Samana Bay, so you are likely to see some whales during your visit.
Saman? is the right place for whale watching.
I was really happy with the trip aboard Victoria 2, and the Kim Beddal crew.
Expensive (55US$), but really informative, saw plenty of whales, and a good amount of jumps (!!!)...