I took Seavis' all-day excursion in July. I didn't do the two island tour as I was more interested in visiting the 'piscina natural' (natural pool). I'm so glad I did! Absolutely stunning, it is. What with starfish at your feet (and in your hands, if you desire), scenery that's at once abundantly beautiful yet otherworldly serene, and a trip with an outfit that exhibits thru their work with endangered turtles, a commitment not only to the locals' economy, but our planet's ecology.
I understand the two island excursion further explores an area that my tour only passed - that is, the point where the Caribbean Sea meets the Atlantic Ocean. That should be a treat, and as with the rest of the day filled with speed boating along the stunning coast of the DR - between stops for drinks and lunch - tours of and relaxation on, stunning, remote beaches - it'll be thrilling beyond belief and stunning beyond measure.
Whichever one you choose - you're winning! :-)
Edited: 4:29 pm, September 06, 2013