I'm with hawkwood on this one. As to the "commando " people, I offer the following true story that is excerpted from The Scuba Snobs' Guide to Diving Etiquette, BOOK 2, which will be out in June. ( Watch for banner ad on this site and announcement in Book and Media Reviews forum.)
We were diving in Bonaire one time with another couple. The guy, we will call him Joe, did not wear anything under his wet suit. He liked to go “commando” when diving. While shore diving one day with this couple, we parked the truck just off the shoulder of a busy road near the airport. The dive site called “Airport” is right there and is a lovely place to dive. In preparation for the dive, Joe wrapped a towel around himself, dropped his swim trunks, pulled up his shorty wet suit under the towel, dropped the towel, then finished donning the wetsuit. No problem. After a couple of dives, to avoid getting too sandy (as if you can avoid that shore diving in Bonaire) Joe climbed into the bed of the pickup truck. While standing there, he peeled his shorty wetsuit down to his waist. Next he wrapped his towel around himself. The next move was to pull his wet suit off the rest of the way, while covered by the towel. This he did, and was still modestly covered by the towel. However, as he was reaching for his swim wear, which we were pretty sure he was going to pull on before removing the towel, his towel was caught by a gust of wind and carried off to the south. Joe was left standing up in the bed of the truck, dressed exactly as he was at the moment of his birth. Joe was a good looking guy, and so it was not surprising that some passers by applauded, others whistled, and some just stood and looked in awe. Unfortunately, some of the witnesses complained. Hence the rule: always wear something under your towel when in public. This is especially important if you are standing on an elevated platform in view of lots of people you don’t know. The rule is a good idea even if you are good looking and in great shape. And if the words good looking or in great shape do not describe you, following this rule is essential.
Don't worry my friends, I never go "commando."
DivemasterDennis