Will Smith can't swim.

The 44-year-old actor's most embarrassing setback in life is never having learned how to negotiate deep waters, but insists he's not scared to get his feet wet as long as his toes can reach the bottom.

Speaking on the Late Show with David Letterman in the US, Will said: "I can't swim. In inner City Philadelphia [where he grew up], there's not a lot of swimming pools and I never actually learnt how to swim and I'm embarrassed about it.

"I'm not scared [of the water]. I get in the water but as long as my feet can touch the bottom, I'm good because I go in, jump up and get some air."

The 'Men in Black 3' actor - who has son, Jaden, 14, and daughter Willow, 12, with wife Jada Pinkett Smith - claims he always ends up red-faced when he watches his kids in the pool, but insists being able to swim isn't a necessity of life.

He explained: "They [Jaden and Willow] can swim because it was important to their mother that they learnt how to swim but you can get through life without that."