If you're looking for a flexible wetsuit base layer that is going to give you added warmth while you're out in the water, then the Orca Base Layer is perfect, whether on it's own or under a wetsuit.
Yamamoto 39cell SCS coated neoprene
0.5mm neoprene with jersey lining makes this base layer easy to get on and off and comfortable against the skin
A long body length with a special gripper hem panel helps to keep water out of the base layer and so increase warmth
A flexy 0.5mm neoprene underarm panel allows for great freedom of movement in this base layer, whether worn by itself or under a wetsuit