On the Day of Joy, Benjamin Watson couldn't stop crying. 

Watson was in Santo Domingo, the capital of the Dominican Republic, leading a group of NFL players as they took a handful of smiling, laughing children on a scavenger hunt through the wonders of an outdoor aquarium.

Everyone else was smiling, enjoying a celebration in the heat of a Dominican summer. Watson found himself heartbroken for a little girl he'd just met. 

Sophia was 7 years old, the same age as one of Watson's five children, wearing braids and pigtails. Before the group split off into teams for the scavenger hunt, she'd been paired with the 37-year-old NFL tight end for an ice-breaker — a difficult ice-breaker given the language barrier; Watson does not speak much Spanish.

Sophia was happy, smiling and energetic.

But Watson knew what she had been through to get to this Day of Joy.

Watson, second-year Saints receiver Austin Carr and five other NFL players traveled to the Dominican Republic in June to partner with the International Justice Mission, the world's largest anti-slavery organization, in the fight against sex trafficking — particularly child exploitation.

For Watson, it was his second trip, a visit with a packed itinerary that included a night spent walking through Santo Domingo's red-light district with investigators, visits to aftercare facilities, presentations by lawyers and a meeting with Margarita Cedeño de Fernández, the Dominican Republic's vice president. The Day of Joy was only a part of the trip, a chance to celebrate with survivors. 

On the way to the aquarium, the players learned about the stories of the six girls and one boy participating in this Day of Joy. Sophia — that's not her real first name; Watson asked The Advocate to keep her name private — had been sexually exploited by a family member for a long time, then finally rescued by the International Justice Mission. 

Watson is no stranger to the fight for the oppressed. One of the leading voices of the NFL's Players Coalition, Watson is an advocate for social justice who has fought for racial reconciliation and prison reform, and last year he traveled to Lebanon to visit Syrian refugees. 

Sophia's story brought it all home.

"For a good few minutes, it just hit me," Watson said. "It’s one thing to read about it on a piece of paper and to know that this is happening around the world. But when you actually reach out and touch this child’s hand, see her little braids, see her little pigtails. ... This is a human being made in God’s image, and for somebody to be so selfish and cruel like that, it really moved me."

Watson and his wife, Kirsten, first heard about the International Justice Mission five or six years ago, through Pro Athletes Outreach, a Christian organization. But the couple decided to fully commit to the International Justice Mission's "Team Freedom" project — an opportunity for athletes to leverage their platform and help raise funds — two years ago. 

"We decided we really wanted to be involved with them, because when it comes to justice, there’s more to justice than 'social' justice," Watson said. "Justice has a lot of different faces."

Based in Washington, D.C., the International Justice Mission is an enormous organization that fights slavery in all its forms, from forced labor to sex trafficking. 

The Watsons chose to focus on sexual exploitation of children, and that led them to the Dominican Republic. The International Justice Mission opened a field office in 2013; what the organization has found about the country's sex trade is troubling.

Although prostitution is legal in the Dominican Republic, many of the women working there were trafficked from other countries, and a study by the International Justice Mission found that "one in 10 individuals engaged in commercial sexual exploitation in the Dominican Republic are children." Eliminate the brothels and focus on the street trade, and the number rises to 23.9 percent.

Watson and Kirsten made their first trip to the Dominican Republic last summer, and along with IJM, they made a presentation to other athletes at the annual Pro Athletes Outreach conference this year. 

Carr was one of the players who responded after talking with his wife, Erica, who has helped establish the Christian organization Athletes in Action in the New Orleans area and has an interest in international policy.

"I knew about it, and obviously, hearing about it was very distressing, but fighting it seemed to be this kind of difficult thing for people who worked full time in legal studies or courtrooms," Carr said. "It wasn’t until I heard about IJM and saw the impact the Watson family has had in this realm that I got really excited to be able to join in and help out."

Watson and Carr were joined by Denver Broncos guard Max Garcia, Chicago Bears tight end Trey Burton, Los Angeles Chargers wide receiver Geremy Davis and long-time NFL veterans Sean Weatherspoon and Nick Novak. 

It didn't take long for the trip to leave an impression. 

On the first night, the group went undercover in Boca Chica with the investigators tasked with finding and arresting traffickers. 

"One of the first things I heard when I got there was a back-and-forth about those guys, saying we have 20, 25 women waiting for you if you want; they’re all 18-24 years old; and they’re all Venezuelan and Colombian girls," Carr said. "It’s heartbreaking to hear them speak about these women. They’re likely not 18-24. Many of them are likely minors, and most of them were trafficked."

The stuff that will stick with Watson and Carr most were the personal moments, the interactions with a trade that often feels far away. 

But the meetings with the vice president, the attorney general and other organizations represent a big step for the International Justice Mission in the Dominican Republic. 

"Since IJM is being able to train judges and the police force, they’re starting to create partnerships with government officials who want to combat the problem as well," Watson said. "That was a big, big step."

For the players, the trip was life-altering. 

Whether an athlete is a 15th-year veteran and outspoken leader like Watson or a second-year player still trying to establish himself like Carr, those four days at the end of June were an opportunity to use their position as a pro athletes to help people in need.

Watson, the leader of the group and a member of the board of Pro Athletes Outreach, let the rest of the players know how much it meant to him to have them on the trip this year.

"So many people say stuff about our league and about who we are, what we don’t do and what we should do, but you guys are giving of yourselves, you and your spouses," Watson told the rest of the players. "I'm proud of you."

And on the Day of Joy, they got to see how much of an impact their assistance can make. 

Follow Joel A. Erickson on Twitter, @JoelAErickson.