If you've ever watched Shark Tank, you know Mark Cuban has some very strong opinions. If he thinks something will fail, he's blunt about saying so. If he thinks you have a great product, he's happy to sing your praises. But how have Cuban's Shark Tank investments actually turned out? In some cases, really, really well.

The personal investment site GOBankingRates recently reviewed 34 of Cuban's most successful investments, with updates on how the companies in question are doing today. You can find the entire list here. These are some of the biggest winners:

1. Tower Paddle Boards

In 2012, Cuban invested $150,000 for a 30 percent stake in this standup paddle board startup. Three years ago, he told Inc.com that Tower Paddle Boards was one of his favorite Shark Tank investments. Later, founder Stephan Aarstol told Success he used most of that initial investment to pay off a $100,000 loan. The Shark Tank appearance generated a quick $60,000 of orders, and when Cuban heard about this he asked for a $50,000 dividend check, which Aarstol paid. So Cuban's initial investment didn't, in itself, help Tower Paddle Boards grow. But Aarstol said, it created a relationship between him and Cuban so that in 2013, when the company couldn't get other financing, Cuban provided a critical $300,000 loan.

Cuban's confidence in the company has paid off. As of 2018, GOBankingRates says, Tower Paddle Boards has made more than $30 million in sales.

2. Nuts 'N More

Nuts 'N More creates nut butters and other products that are high in protein and contain flax seed, some of them in flavors such as mint chocolate chip or spiced pumpkin pie. In 2013 Cuban and fellow Shark Robert Herjavec partnered up to invest $250,000 for 35 percent of the company. It was another one of Cuban's favorite investments, he said, mainly because he's always looking for healthy foods that can appease his desire for sweets. But it turned out to be a lucrative bet, as well. As of 2018, the company had more than $30 million in total sales, according to GOBankingRates.

3. Gameday Couture

Gameday Couture attempts to solve a common female complaint: You want to wear apparel that supports your favorite sports team, but most of what's available lacks fashion appeal and was created with men in mind. Gameday Coutoure works with NBA and NCAA teams to create clothing with team logos and fashionable touches. 

Cuban invested $100,000 in 2014 for a 30 percent stake in the company, on one condition: It had to design a line of apparel for his team, the Dallas Mavericks. Now Cuban not only has a stylish assortment of Mavericks tops to offer his team's female fans, he also has a slice of a very successful company. Gameday Couture was projecting total sales of $20 million by the end of 2018, and $12 million for 2018 alone. 

4. Simple Sugars

Lani Lazzari was only 19 when she pitched her skin care line on Shark Tank in 2013, having delayed a year of high school to focus on her company, and then deciding to skip college altogether. Cuban invested $100,000 for 33 percent of the company because Lazzari reminded him of himself, and, like him, came from Pittsburgh. It turned out to be a smart investment. Simple Sugars had just under $2 million in sales in 2017, and expects to reach $5 million in annual sales within the next couple of years.