Hi ibdiving,
Thermal comfort is a rather individual matter.
Have you ever been out on the street in the spring or fall and noticed people wearing everything from shorts & T-shirts to full coats with hats & scarves, all apparently in comfort? Well, things are no different underwater. This comfort is highly variable among individuals depending on such factors as percentage of body fat, age & tolerance to thermal discomfort. Other determinants, like how many dives a day over how many days you are planning, are also important. When you ask such a question, you'll get answers ranging all the way from 'just a bathing suit' through '5 mm full.'
The question might better be phrased: 'What water temps can I anticipate in the northern Red Sea in March?' You can receive a pretty accurate answer to this, and then can decide what's best for you based on your personal thermal comfort needs.
That having been said, Red Sea Turk water temps in March should be 71 +/- 2 degrees. I can tell you that if I was doing 5-7 days diving in that temp range I would take my 5 mm full, plus a hooded vest. Whether this would work for you, I cannot say. I like being warm.
You should have a smashing time
DocVikingo
