Is this for cruise excursions? If so, I would go directly through your cruise line. I have no idea if Punta Cana even has a port--I am just guessing that's what you mean b/c I always refer to excursions for cruises. Anyway, although I *LOVE* Punta Cana (and honeymooned there) it can definitely still be a bit 'shady'. So if you're not on a cruise, I'd pick a reputable tour operator through your hotel concierge.