Swimming at the 2015 World Aquatics Championships – Men's 800 metre freestyle
The men's 800 metre freestyle competition of the swimming events at the 2015 World Aquatics Championships was held on 4 August with the heats and 5 August with the final.Records
Prior to the competition, the existing world and championship records were as follows.Results
Heats
The heats were held at 10:30.
| Rank | Heat | Lane | Name | Nationality | Time | Notes |
| 1 | 5 | 3 | Connor Jaeger | | 7:44.47 | Q |
| 2 | 5 | 4 | Gregorio Paltrinieri | | 7:45.15 | Q |
| 3 | 5 | 2 | Stephen Milne | | 7:46.61 | Q |
| 4 | 5 | 6 | Michael McBroom | | 7:47.05 | Q |
| 5 | 5 | 5 | Mack Horton | | 7:47.08 | Q |
| 6 | 4 | 5 | Sun Yang | | 7:47.87 | Q |
| 7 | 5 | 8 | Wojciech Wojdak | | 7:48.95 | Q |
| 8 | 3 | 6 | Henrik Christiansen | | 7:49.70 | Q, NR |
| 9 | 5 | 1 | Ahmed Akram | | 7:49.83 | NR |
| 10 | 4 | 4 | Ryan Cochrane | | 7:50.28 | |
| 11 | 4 | 2 | Damien Joly | | 7:50.30 | |
| 12 | 4 | 0 | Marc Sánchez | | 7:51.19 | |
| 13 | 3 | 0 | Mads Glæsner | | 7:51.24 | NR |
| 14 | 3 | 5 | Joris Bouchaut | | 7:52.37 | |
| 15 | 4 | 1 | Florian Vogel | | 7:53.61 | |
| 16 | 4 | 9 | Maarten Brzoskowski | | 7:54.31 | |
| 17 | 4 | 3 | Pál Joensen | | 7:55.01 | |
| 18 | 3 | 4 | Richárd Nagy | | 7:55.31 | NR |
| 19 | 5 | 9 | Wang Kecheng | | 7:56.05 | |
| 20 | 3 | 7 | Nathan Capp | | 7:57.61 | NR |
| 21 | 3 | 8 | Martín Naidich | | 7:57.72 | |
| 22 | 4 | 8 | Sören Meißner | | 7:57.93 | |
| 23 | 5 | 7 | Gergely Gyurta | | 7:58.70 | |
| 24 | 4 | 6 | Péter Bernek | | 7:59.56 | |
| 25 | 3 | 1 | Serhiy Frolov | | 8:02.17 | |
| 26 | 3 | 2 | Esteban Enderica | | 8:03.17 | |
| 27 | 3 | 9 | Martin Bau | | 8:04.11 | |
| 28 | 5 | 0 | Myles Brown | | 8:04.47 | |
| 29 | 2 | 5 | Vuk Čelić | | 8:05.68 | |
| 30 | 4 | 7 | Jan Micka | | 8:05.76 | |
| 31 | 3 | 3 | Matias Koski | | 8:07.28 | |
| 32 | 2 | 6 | Sven Arnar Saemundsson | | 8:07.40 | NR |
| 33 | 2 | 1 | Ido Haber | | 8:07.78 | |
| 34 | 2 | 2 | Alexei Sancov | | 8:10.83 | |
| 35 | 2 | 3 | Marcelo Acosta | | 8:12.52 | |
| 36 | 2 | 4 | Ernest Maksumov | | 8:12.65 | |
| 37 | 1 | 4 | Alin Artimon | | 8:17.16 | |
| 38 | 2 | 8 | | | 8:18.20 | |
| 39 | 2 | 7 | Andy Arteta | | 8:19.39 | |
| 40 | 1 | 5 | Felipe Tapia | | 8:21.27 | |
| 41 | 1 | 3 | Pol Arias | | 8:28.11 | |
Final
The final was held at 18:58.
| Rank | Lane | Name | Nationality | Time | Notes |
| 7 | Sun Yang | | 7:39.96 | |
| 5 | Gregorio Paltrinieri | | 7:40.81 | ER |
| 2 | Mack Horton | | 7:44.02 | |
| 4 | 4 | Connor Jaeger | | 7:44.51 | |
| 5 | 8 | Henrik Christiansen | | 7:45.66 | NR |
| 6 | 1 | Wojciech Wojdak | | 7:45.90 | NR |
| 7 | 3 | Stephen Milne | | 7:49.86 | |
| 8 | 6 | Michael McBroom | | 7:55.30 | |
