Guidance on equipment to use in the Race is often found on the Race web-site. However, the basic list below will be of use to anyone who has never raced or is inexperienced.
Swimwear or trisuit, goggles, swim hat unless supplied. For open water in the UK, a neoprene wetsuit is usually compulsory. Check the race website for advice.
Road or triathlon-specific bike, tribars, helmet, cycle shoes/trainers, cycle top/t-shirt (or tri suit top). Race number belt (safety pins will usually be provided at registration). Remember you must wear a visible race number on your back when on the bike. Any nutritional requirements according to length of race and whether provided by race organisers. Energy drinks and gels, other food according to distance.
Talc for inside your cycling shoes or trainers (helps get them on quicker)
Trainers, socks (if wearing), t-shirt/top or trisuit top. Remember you must wear a visible race number on your front when running.
Drink – make sure you stay hydrated before, during and after the race.