When the three co-founders of Sand Cloud pitched their startup on Shark Tank last year, they were selling colorful Turkish towels and a mission to protect marine life. Now they've expanded to accessories and clothing, with a promise to sell only sustainable apparel by the summer of 2019, betting those updates will click with environmentally conscious 
consumers--and so far, they've been right.

"We realized we had a brand and people felt comfortable repping Sand Cloud as a company," says Brandon Leibel, one of its co-founders. "We wanted to take advantage of that and give people from all over the world--who don't necessarily live by the beach--an opportunity to represent Sand Cloud and what we stand for."

The San Diego-based startup donates 10 percent of profits to charitable organizations that aim to protect marine life, including the Marine Conservation Institute and the Pacific Marine Mammal Center. Leibel, Steven Ford, and Bruno Aschidamini launched Sand Cloud in 2014, quitting their day jobs and working as Uber drivers on the side to support the business.

Sand Cloud did about $6 million in sales last year, an increase of $3.6 million from 2016. Part of that jump came from the company's appearance on Shark Tank, where Robert Herjavec offered the trio $200,000 for 15 percent of the business. However, the company's new offerings don't hurt.

Sand Cloud now sells T-shirts, jewelry, and accessories such as water bottles and, in March, launched a VIP subscription box that sends customers a T-shirt and pair of socks each month. Customers will feel the biggest changes at Sand Cloud as the startup moves toward a fully sustainable clothing line, meaning fabrics derived from eco-friendly sources.

Sand Cloud is working with Recover, a Charlotte, North Carolina-based business that turns plastic bottles and recycled cotton into garments, to make all of its apparel embody the Sand Cloud mission. While this will increase production costs--Leibel estimates there is a $1 difference between a traditional shirt and one made from recycled materials--Sand Cloud has no plans to hike prices just yet. Leibel added that the new shirts are softer than its previous versions. 

Sand Cloud isn't the first company to opt for a sustainable clothing line. In fact, that's been the industry trend recently, according to Katie Smith, an analyst and insights director at the retail analytics firm Edited. She said the industry's shift toward recycled or sustainable materials has increased in the past 12 to 18 months due to a growing concern about the environment. Additionally, customers want purchases to reflect their values, even when it comes to the environment.

"Our lifetime fans that will support us with any product we come out with because it's more than just buying the product," Leibel says. "They are buying into the mission and what we stand for."