What you are looking at are members of the St. Thomas Aquinas and Belen Jesuit water polo teams lining up to shake hands after their state championship match in Miami. What you are also looking at is one of the Belen players deciding to go out with a flourish.
According to the Miami Herald, that shove led to a bit of a scuffle, although no punches were thrown:
After the game, physical play spilled over to the awards ceremony when the teams momentary got into a scrum. While no punches were thrown, the teams had to be separated after a Belen player allegedly pushed an Aquinas player into the pool as the teams were lined up to congratulate each other. The tensions were quickly softened as both teams went on to receive their medals. After the ceremony, several Belen players came to the St. Thomas’ side of the pool deck to apologize and congratulate their opponents.
We don't know who the kid who did the shoving is, but we do know that he has absolutely no fucks left to give.
Oh, and here's a GIF, from a different angle: