Triathlon - What does one wear under a wetsuit?

[Roar]

Hi there.

I have entered a triathlon with some work-mates at the last minute... it's in 3 weeks.

It's a sprint, so I think I will be OK for the swimming and the cycling...and I can run a 5k but I will be slow.

My question is - what do I wear? I will have to wear a wetsuit for this as the water is going to be pretty cold. What do you wear underneath it?

I'd like to be as speedy as possible in the transitions, so I would be grateful for any tips and tricks you'd like to throw my way. (I will also take any advice on how to get speedier on the run, though that might be a topic for some other forum....)

Many thanks.