You probably could - but I'm pretty sure that all of the host shops at the major shore sites (ie Eden Rock at Eden Rock/Devil's Grotto, Sunset House at Sunset Reef, Sun Divers at Robert's/Turtle Farm Reef and DiveTech at Lighthouse Point and Cobalt Coast) all offer guided dives and or guides for hire. I know for a fact that Sun Divers does as I saw it on their board when I was there last week.
In response to your earlier question about marine life, you can expect to see lots of fish - snappers, jacks, grunts, tarpon, hogfish, sgt. majors, angels, butterflies, soapfish, grouper, wrasses, rays, barracuda, durgons, parrotfish, squirrelfish, scorionfish, puffers, trumpetfish, goatfish, chromis, cowfish, filefish, trunkfish, tangs, flounder, eels, lobster, shrimp, crabs, hard and soft corals, anemones, hydroids, sponges, and turtles too - pretty much all of the usual suspects expected on caribbean reefs.