Top swimmers from across the country will be vying for national titles and the opportunity to represent the United States overseas later this summer at the World Aquatics Championships, the World Aquatics Junior Championships, the LEN (European Swimming Federation) U23 Championships and the Pan American Games.

The list of the 634 competitors reads like a proverbial who’s who of American swimming, including the return of Caeleb Dressel (Green Cove Springs, Fla./Gator Swim Club) and Erica Sullivan (Las Vegas, Nev./Longhorn Aquatics) to national competition. Overall, 38 Olympians and 31 Olympic medalists are registered to compete.

With national titles and international team roster slots on the line, here are five things to watch at this year’s Phillips 66 National Championships:

• Record setters: Across the 34 events to be contested, 21 American record holders are slated to compete. Four swimmers also hold world records: Hunter Armstrong (50m backstroke), Dressel (100m butterfly), Lilly King (100m breaststroke) and Katie Ledecky (800m freestyle, 1500m freestyle).
• Ledecky and Kalisz Go for Six: Katie Ledecky and Chase Kalisz have competed in every World Championships since 2013, a total of five competitions. If they are named to this year’s team, they join an elite group of American athletes – Nathan Adrian, Elizabeth Beisel, Natalie Coughlin, Ryan Lochte and Michael Phelps – that have qualified for six World Championships. Ledecky and Kalisz are each entered in four events in Indianapolis.
• Return of the Champions: Ten gold medalists from 2022’s World Championships in Budapest, Hungary will be competing for a chance to defend their titles this year in Fukuoka, Japan.
• International Opportunities Abound: In total, there are 154 roster spots available on the four teams selected at the National Championships. USA Swimming has never selected athletes for so many teams at one meet.
• World Championships First: The only team named on site at this event will be the swimmers competing at the World Aquatics Championships next month in Fukuoka, Japan. The rosters for the World Aquatics Junior Championships, the LEN U23 Championships and the Pan American Games will be released later.