I'm doing 3 day weight training. I was wondering whether it's OK to swim on my rest days. My workout is as follows

Monday - Chest, Shoulders, Forearms, Abs
Tuesday - Rest (Planing to swim - is that OK?)
Wednesday - Back, Triceps, Abs
Thursday - Rest (Planing to swim - is that OK?)
Friday - Legs, Biceps, Forearms, Abs

Please tell me if this is OK

Sound like you have an awesome work out schedule, just make sure you eating enough food for the calories that your burning and drinking lots of water to keep yourself hydrated.