Complex sentence: In an indoor pool, for lane swim, bathers will typically wear lycra briefs (men) or lycra one-piece tanksuits (women), but on a beach, or especially on an urban beach, something more substantial is preferably worn.
Split into simpler sentences: In an indoor pool, bathers will typically wear lycra briefs (men) or lycra one-piece tanksuits (women). On a beach, especially an urban beach, however, something more substantial is preferably worn.