It seems this is a resort that caters mainly for Egyptians and Libyans and your friend is likely to be more at ease than a westerner, yourself included. Those of these nationalities who go there will enjoy themselves for the same reasons others do - they are on a holiday with family and/or friends, but their conduct will in many ways be quite different from, say, what you see at a seaside resort in Portugal or Spain. The men and children will be raucous, the women generally quite reserved. If you conform to local norms you will presumably fare better than if you do not - this will indeed very probably rule out sunbathing and only permit swimming fully dressed and you will very possibly be readily identifiable as an outsider. Unless both nationalities have changed their attitudes Libyans and ordinary Egyptians do not sunbathe nor do they own swimsuits, except for the men of course who swim in shorts. Obviously, if you are completely alone you can do more or less what you like, including skinny-dipping.