The women's 800 metre freestyle competition at the 2023 World Aquatics Championships was held on 28 and 29 July 2023.

Records Prior to the competition, the existing world and championship records were as follows.

Results Heats The heats were started on 28 July at 12:13.

Rank Heat Lane Name Nationality Time Notes 1 4 4 Katie Ledecky 8:15.60 Q 2 3 6 Li Bingjie 8:20.51 Q 3 3 5 Erika Fairweather 8:21.06 Q 4 3 4 Ariarne Titmus 8:21.25 Q 5 4 5 Lani Pallister 8:21.38 Q 6 4 3 Simona Quadarella 8:21.65 Q 7 3 3 Isabel Gose 8:21.71 Q 8 4 6 Jillian Cox 8:22.20 Q 9 4 7 Anastasiia Kirpichnikova 8:22.74 10 4 0 Ajna Késely 8:28.23 11 3 1 Waka Kobori 8:29.54 12 4 1 Eve Thomas 8:31.72 13 3 0 Beatriz Dizotti 8:32.42 14 2 6 Alisée Pisane 8:32.52 NR 15 3 7 Deniz Ertan 8:32.54 16 4 8 Miyu Namba 8:34.62 17 2 8 Gan Ching Hwee 8:36.31 18 2 2 Emma Finlin 8:36.47 19 2 5 Kristel Köbrich 8:37.09 20 4 2 Yang Peiqi 8:37.16 21 4 9 Jimena Pérez Blanco 8:37.40 22 3 2 Merve Tuncel 8:39.47 23 3 8 Ángela Martínez 8:39.60 24 2 3 Bettina Fábián 8:39.63 25 3 9 Tamila Holub 8:42.90 26 2 7 Han Da-kyung 8:43.68 27 2 4 Gabrielle Roncatto 8:48.36 28 2 0 Artemis Vasilaki 8:49.61 29 2 1 Imani de Jong 8:50.81 30 1 6 Diana Taszhanova 8:51.46 NR 31 1 4 María Bramont-Arias 8:59.52 32 1 5 Eva Petrovska 9:06.00 33 1 3 Sasha Gatt 9:08.63 34 2 9 Võ Thị Mỹ Tiên 9:15.23

Final The final was held on 29 July at 21:23.

Rank Lane Name Nationality Time Notes 4 Katie Ledecky 8:08.87 5 Li Bingjie 8:13.31 AS 6 Ariarne Titmus 8:13.59 =OC 4 7 Simona Quadarella 8:16.46 5 1 Isabel Gose 8:17.95 6 8 Jillian Cox 8:19.73 7 2 Lani Pallister 8:21.33 8 3 Erika Fairweather 8:28.21

References