Victoria's Secret's most successful product isn't lingerie

Victoria's Secret's swimwear sales are soaring.

Swimwear sales were up more than 10% in the first quarter, compared with an overall sales increase of 5%, CEO Sharen Jester Turney told investors on a recent conference call.

The brand sells a variety of mix-and-match swimsuit tops and bottoms.

Like Victoria's Secret lingerie, the swimsuit tops are padded and designed to enhance curves. The company is known for having the best selection of swimwear.

Victoria's Secret capitalized on the popularity of the line by hosting a swimwear special similar to its annual fashion show.

Victoria's Secret has also built a huge sportswear brand in just two years.

The brand's Sport line grossed between $200 and $250 million in annual sales from $0 two years ago, according to a recent report by Morgan Stanley.

Analysts say the brand could eventually grow to $1 billion.

Victoria's Secret plans to add the Sport line to 150 more stores this spring.

"We're very excited and very pleased with our sport business, especially in our bra category," CEO Sharen Jester Turney told investors. "That's where we've been putting a lot of our emphasis and seeing tremendous growth."

Victoria's Secret controls 35% of the US lingerie market and has millions of customers.