St. Martin is undoubtedly the most beautiful place to visit in Bangladesh. You can see the true beauty of Bangladesh while traveling to St. Martin. Teknaf itself is very wonderful place to enjoy as one can see the beauties of both hills and sea at a time from Teknaf. Who ever used the Marine Drive road for a once can never forget its beauty.
You have nicely described about the island how to reach St. Martin's Island using Teknaf and it is the easiest way to go there enjoy the most beautiful place in Bangladesh. But, I, humbly, want to add two more information. One can also go to St. Martin's Island by Karnafuli Express(ship) from Cox's Bazar. And, recently a cruise ship "Bay One" is also available from Chittagong to St. Martin's Island.
I have a dream to make a tour with the members of BDCommunity, In Shah Allah. What would you say, Fahim brother?