In swimming’s finale, the U.S. men keep their unbeaten streak alive, and Emma McKeon gets her 7th medal.

TOKYO — The medals, dozens of them, arrived in singles and in bunches, in short races and long ones, in medleys and relays. But every day, it seemed, the United States and Australia tossed a few more on the pile. Sunday was no different.

Emma McKeon of Australia became the second woman to win seven medals in a single Olympics, and Caeleb Dressel and Bobby Finke of the United States added more gold medals to the American haul on a frantic final day of the swimming competition at the Tokyo Aquatics Center.

The United States finished the meet by winning the men’s 4×100-meter medley relay in world-record time, extending an American unbeaten streak in the event. The victory also gave Dressel, who won the men’s 50 freestyle in Sunday’s opening race, his fifth gold medal of the Games.

Dressel, 24, became only the fifth American to win five golds in a single Games, joining a list that includes some of the greatest Olympians in the country’s history: the speedskater Eric Heiden and the swimmers Mark Spitz, Matt Biondi and Michael Phelps. (Phelps accomplished the feat three times.)

“I’m proud of myself,” Dressel said afterward. “I feel like I reached what my potential was at these Games, and it was really fun racing.”

The American swimmers finished the Olympic meet with 30 total medals, down from the 33 they won in Rio de Janeiro in 2016. And their final total of 11 gold medals fell short of the 16 they took home from the last Games.

In some ways, then, the team has looked like a group in transition. Afterward, the coaches said they hoped their young athletes had gained valuable experience for the next Olympics, now only three years away.

“Of course we’d love to have more golds here, just like we’d love to have more medals in general,” said Greg Meehan, the women’s team coach. “I think we had four fourth places.”

McKeon, 27, had started the day knowing that a top-three finish in her two races — the 50 free and the 4×100 medley relay — would make her only the second woman, after the Soviet gymnast Maria Gorokhovskaya in 1952, to win seven medals at a single Olympics. By day’s end, she had won gold in both.

In her first race, McKeon emerged from a highly competitive field to take gold in the women’s 50 freestyle, finishing with a time of 23.81 seconds, an Olympic record. Sarah Sjostrom of Sweden was second (24.07 seconds) and Pernille Blume of Denmark, who won gold in 2016, took third (24.21). Abbey Weitzeil, the only American in the final, finished last.

Later, in the women’s 4×100 medley relay, Australia won the gold medal with a time of 3:51.60. The American women, who won gold in the event at the 2016 Games, settled for the silver. Canada took the bronze.

McKeon erased a small U.S. lead with her butterfly leg, and Cate Campbell delivered the final touch after a powerful closing freestyle. While McKeon picked up her seventh medal — and her fourth gold — in the race, Campbell collected her fourth. She finished the Games with three golds and a bronze.

McKeon said the day had felt surreal. “To be in that kind of company, it’s an honor,” she said of tying a record for medals at a single Games. “And I know I’ve worked hard for it.”

Her total ran Australia’s medal count to 20, with nine golds, meaning that the Aussies and the Americans together had won nearly half of the medals available (50, of 105) and more than half the golds.

Wedged between some of the superstars of the sport, Finke, 21, had been a relative unknown before this month. On Sunday, he won his second gold medal by prevailing in the men’s 1,500-meter freestyle after an intense three-man showdown with Mykhailo Romanchuk of Ukraine and Florian Wellbrock of Germany.

Finke hung close for most of the race and then propelled himself into the lead with his final turn. Finding a new gear after 29 relentlessly steady laps, he beat his rivals to the wall. He finished in 14 minutes 39.65 seconds, a body length ahead of Romanchuk (14:40.66) and Wellbrock (14:40.91).

His victory, and Katie Ledecky’s in the women’s event, gave the United States a sweep of the grueling 30-lap swimming marathons, the longest races in the competition.

“I don’t know how I’m going to be able to process things,” Finke said afterward. “I came into to this meet not really expecting to medal for anything.”

Dressel had entered the meet with much higher expectations. He opened the session by winning his fourth gold medal of the Games with a lung-busting sprint to victory in the 50 free. Diving off the blocks, he surfaced in the lead and never gave it up — or took a breath — as he finished in 21.07 seconds, an Olympic record. Florent Manaudou of France finished second in 21.55 seconds, and Bruno Fratus of Brazil (21.57) came in third.

When Dressel learned that he had won, he flexed his left bicep and then hustled out of the pool to prepare for the day’s final race, the 4×100 medley relay.

Dressel had entered the pool Sunday having already won three gold medals at the Games, in the 4×100 freestyle relay, the 100 free and the 100 butterfly. His time in the 100 butterfly, 49.45 seconds, was also a world record.

History was on the line in the final event, the men’s 4×100 medley relay. The American men entered the competition having won gold in every Olympics they had competed in — they did not participate in 1980, when the United States boycotted the Moscow Olympics — and kept the streak alive with a world record, winning easily in 3:26.78.

Despite their dominance, the Americans had entered the race as underdogs. The Americans had nearly missed the final, in fact, qualifying seventh with a different set of swimmers. That left the group that strode onto the deck for the final — Ryan Murphy, Michael Andrew, Dressel and Zach Apple — in an outside position, in Lane 1, but with a better-than-outside shot.

Dave Durden, the head coach of the men’s team, said he knew the team had a shot when he looked at splits from the previous world-record time and saw that each of the American men was individually capable of beating them.

“All we wanted them to do was swim at their level,” said Durden, who added that Dressel’s earlier swim had freed him mentally to perform well in the relay.

Murphy, the world-record holder in the 100 backstroke, staked the Americans to an early lead, before Adam Peaty of Britain, the world’s fastest man in the breaststroke, immediately erased the advantage by the race’s halfway mark.

But the Americans were just too deep. Dressel powered back in the butterfly, and Apple kept the United States streak alive with a strong closing freestyle leg. Britain won the silver and Italy took the bronze.

After a grueling week and a half of swimming, and an Olympic cycle that lasted five years instead of four, Dressel joked that he was ready to go home.

“I’m going to take a little break here,” he said, laughing. “I’m pretty over swimming, guys.”