Heats
dimanche 12 août 2018, 03h00 GMT – 10h30 GMT
| Nom | Équipe | Temps | |
|---|---|---|---|
| 1 |  Zane Grothe | United States | 7′ 43.74″ |
| 2 |  Jordan Wilimovsky | United States | + 1.45″ |
| 3 |  Jack McLoughlin | Australia | + 3.57″ |
| 4 |  Guilherme Costa | Brazil | + 7.93″ |
| 5 | Robert Finke | United States | + 8.83″ |
| 6 | Mack Horton | Australia | + 9.68″ |
| 7 | Naito Ehara | Japan | + 11.28″ |
| 8 | Shogo Takeda | Japan | + 12.27″ |
| 9 | Michael Brinegar | United States | + 15.05″ |
| 10 | Kohei Yamamoto | Japan | + 15.3″ |
| 11 | Alex Pratt | Canada | + 19.38″ |
| 12 | Jeremy Bagshaw | Canada | + 19.64″ |
| 13 | Ayatsugu Hirai | Japan | + 20.89″ |
| 14 | Peter Brothers | Canada | + 21.63″ |
| 15 | Grant Shoults | United States | + 25.61″ |
| 16 | Wesley Roberts | Cook Islands | + 38.88″ |
| 17 | Noel Keane | Palau | + 1′ 41.14″ |
| 18 | Mark Imazu | Guam | + 2′ 23.72″ |