The captain of a 25-foot tugboat that was pushing a barge when it slammed into a sailboat last year in Miami Beach, killing three children from a sailing camp, pleaded guilty on Tuesday to a count of seaman’s manslaughter.

The captain, Yusiel Lopez Insua, 47, of Miami, admitted in U.S. District Court for the Southern District of Florida that his actions caused the collision, according to court documents. He faces up to 10 years in prison.

Prosecutors said Mr. Insua was pushing a barge across Biscayne Bay just before 11:30 a.m. on July 28, 2025, when it struck a stalled sailboat carrying five girls, ages 7 to 13, and a 19-year-old camp counselor. The Miami Yacht Club said the children and the counselor were from a sailing camp run by the Miami Youth Sailing Foundation.

The yacht club, a fixture of the waterfront since 1927, runs summer programs where children and teenagers learn to navigate the winds through sailing, windsurfing and paddle boarding. The club provides an eight-week seasonal course. The 2025 session was entering its final week of instruction when the incident occurred.

The U.S. Coast Guard received a report that a barge had struck the sailboat near Hibiscus and Monument islands in Miami Beach.

Three of the girls were killed. The Miami-Dade County Medical Examiner’s Office identified two of them as Mila Yankelevich, 7, and Erin Ko, 13. Days later, the family of a third victim, Arielle Buchman, 10, announced that she, too, had died.

Federal prosecutors said that the camp counselor had tried to alert Mr. Insua to the sailboat’s presence, but that his forward view was blocked by part of the tugboat’s structure. Investigators conducting a forensic analysis of Mr. Insua’s phone found evidence of internet activity around the time of the collision, according to prosecutors.

“Three children lost their lives in a tragedy that never should have happened,” Jason A. Reding Quiñones, U.S. attorney for the Southern District of Florida, said in a statement.

Mr. Insua’s lawyer did not immediately respond to a request for comment. The families of the victims did not immediately respond to a request for comment.

Sheelagh McNeill contributed research.