Leon Marchand and Summer McIntosh sealed their golden swimming world championships with dominant victories on Sunday's final day as the United States signed off with a relay record.

Eight days of competition in Singapore wrapped up with French superstar Marchand and 18-year-old Canadian sensation McIntosh underlining their supremacy.

Marchand, who won four individual golds and was the face of his home Paris Olympics a year ago, added the 400-meter individual medley crown to his 200 medley title this week.