While the media has reported the delay of the women’s 10 km swim at the 2025 World Aquatics Championships due to poor water quality, there is also another issue that may plague the open water races scheduled to be held this week on Sentosa Island: warm water.

The water temperatures are reportedly between 30.4°C and 31.1°C (86.7°F – 88°F) which is right at or exceeding the borderline of the 31.0°C (87.8°F) maximum allowable temperature. This standard was selected as a result of the 2010 death of Fran Crippen in a FINA World Cup race due to hyperthermia.

But whether the water temperature is 30.4°C or 30.9°C by the start of the races, there are three issues that will make the effective water temperature even warmer:

• The swimmers wear all-black, skin-tight, full-body techsuits in competition.
• While the men’s races start in the early morning at 7:30 am, the women’s races start at 10:30 am when the sun is higher in the sky and the solar radiation becomes greater.
• Water temperature readings at taken before the race starts, but the races are not stopped even if the maximum allowable water temperatures are exceeded later in the day.

Every competitive swimmer knows that they feel relatively warmer in their all-black, skin-tight, full-body techsuits compared to wearing their porous training suits in workouts. Those techsuits (shown above on Florian Wellbrock on left, 27, Germany, MSF bio here, World Aquatics bio here, @flo.swim and Kristóf Rasovszky on right, 28, Hungary, MSF bio here, World Aquatics bio here, @kristofrasovszky) are very effective in trapping the elevated body heat while racing up to two hours in the 10 km races.

Starting the races earlier (men’s 10 km + 3 km Knockout Sprints + 6 km Mixed Relays) does help, the women will unfortunately not gain that benefit later in the day. There is precedence for the races starting early: at the 2011 World Championships in Shanghai where the water temperature exceeded 31°C, the 25 km race was started very early (before 6 am if my memory is correct). But even in these races, dozens of swimmers were pulled from the water with hyperthermia and either received medical care or were rushed to local hospitals.

Undoubtedly, managing one’s elevated core body temperatures will play a major role in who will earn podium positions this week in Singapore.

But like most conditions and situations in the open water, the athletes have prepared well for these conditions and will swim as well as they can.

Men’s 10 km Start List

1. Joaquin, 27, Argentina
2. Kyle Lee, 23, Australia
3. Nicholas Sloman, 27, Australia
4. Luca Karl, 23, Austria
5. Logan Vanhuys, 28, Belgium
6. Santiago Castedo, 16, Bolivia
7. Alejandro Plaza, 19, Bolivia
8. Luiz Felipe Loureiro, 21, Brazil
9. Matheus Melecchi, 19, Brazil
10. Eric Georges Brown, 22, Canada
11. Tianchen Lan, 20, China
12. Jinhou Zhang, 22, China
13. Juan Manuel Morales, 24, Columbia
14. Jeison Rojas, 22, Costa Rica
15. Martin Straka, 24, Czech Republic
16. Juan Diego Nunez Barreras, 19, Dominican Republic
17. Esteban Enderica Salgado, 34, Ecuador
18. David Farinango, 24, Ecuador
19. Marc-Antoine Olivier, 29, France
20. Jules Wallart, 22, France
21. Hector Pardoe, 24, Great Britain
22. Oliver Klemet, 23, Germany
23. Florian Wellbrock, 27, Germany
24. Konstantios Chourdakis, 16, Greece
25. Jose Barrios, 17, Guatemala
26. Oscar Garcia, 16, Guatemala
27. Tsun Hin Chan, 20, Hong Kong
28. Chin Ting Keith Sin, 30, Hong Kong
29. Diego Dulieu, 20, Honduras
30. David Betlehem, 21, Hungary
31. Kristóf Rasovszky, 28, Hungary
32. Alexander Adrian, 17, Indonesia
33. Aflah Fadian Prawira, 27, Indonesia
34. Army Pal, 23, India
35. Anurag Singh, 22, India
36. Yonatan Ahdut, 21, Israel
37. Matan Roditi, 26, Israel
38. Andrea Filadelli, 24, Italy
39. Gregorio Paltrinieri, 30, Italy
40. Riku Takaki, 20, Japan
41. Kaito Tsujimori, 19, Japan
42. Lev Cherepanov, 24, Kazakhstan
43. Samir Bachelani, 19, Kenya
44. Swaleh Abubakar Talib, 25, Kenya
45. Sebeom Oh, 22, South Korea
46. Jaehun Park, 25, South Korea
47. Alian Gonzalez Torres, 18, Mexico
48. Diego Obele Cisneros, 23, Mexico
49. Theo Druenne, 19, Monaco
50. Estaban Faure, 17, Monaco
51. Denis Adeev, 27, Neutral Country B
52. Vladislav Utrobin, 26, Neutral Country B
53. Nico Joaquin, 19, Namibia
54. Joaquin Estigarribia,19, Paraguay
55. Adrian Gustavo Ywanaa Papi, 20, Peru
56. Bartosz Kapala, 18, Poland
57. Piotr Wozniak, 19, Poland
58. Tiago Campos, 26, Portugal
59. Diogo Cardoso, 24, Portugal
60. Jamarr Andre Bruno, 20, Puerto Rico
61. Ruan Breytenbach, 23, South Africa
62. Connor Buck, 22, South Africa
63. Damien Payet, 21, Seychelles
64. Artyom Lukasevits, 20, Singapore
65. Ritchie Oh, 22, Singapore
66. Tharusha Rangitha Perera, 18, Sri Lanka
67. B Dilanka Shehan, 26, Sri Lanka
68. Adam Ahmed Yacoub Ahmed, 16, Sudan
69. Gafar Hassan, 22, Sudan
70. Paul Niederberer, 21, Switzerland
71. Christian Schreiber, 23, Switzerland
72. Jakub Gabriel, 19, Slovakia
73. Tomas Pavelka, 17, Slovakia
74. Nithikorn Jeampiriyakul, 20, Thailand
75. Ratthawit Thammaanthachote, 22, Thailand
76. Cheng-Chi Cho, 26, Chinese Taipei
77. Bo Ling Su, 14, Chinese Taipei
78. Rami Rahmouni, 16, Tunisia
79. Dylan Gravley, 22, USA
80. Joey Tepper, 23, USA
81. Diego Vera, 29, Venezuela
82. Ronaldo Eduardo Zambrano Sanchez, 23, Venezuela

Women’s 10 km Start List

1. Alexandra Mejia Gallego, 19 Andorra
2. Candela Gordanino, 21, Argentina
3. Britta Schwengle, 21, Aruba
4. Chelsea Gubecka, 26, Australia
5. Moesha Johnson, 27 Australia
6. Ana Marcela Cunha, 33, Brazil
7. Viviane Jungblut, 29, Brazil
8. Emma Finlin, 20, Canada
9. Yaxin Liu, 26, China
10. Kexin Wang, 20, China
11. Alena Benesova, 27 Czech Republic
12. Christina Duran, 20, Dominican Republic
13. Isabella Hernandez, 20, Dominican Republic
14. Ana Abad, 21, Ecuador
15. Danna Martinez, 19, Ecuador
16. Dayana Melendez, 18, El Salvador
17. Maria de Valdes, 26, Spain
18. Angela Martinez Guillen, 21, Spain
19. Louna Kasvio, 19, Finland
20. Leonie-Sarah Josephine Tenzer, 19, Finland
21. Ines Delacroix, 22, France
22. Caroline Laure Jouisse, 31, France
23. Lea Boy, 25, Germany
24. Jeannette Spiwoks, 26, Germany
25. Georgia Makri, 19, Greece
26. Maria Porres, 22, Guatemala
27. Yanci Vanegas, 22, Guatemala
28. Pac Tung Nikita Lam, 24, Hong Kong
29. Tsz Yin Nip, 25, Hong Kong
30. Janka Juhasz, 25, Hungary
31. Viktoria Mihalyvari-Farkas, 21, Hungary
32. Ashmitha Chandra, 19, India
33. Diksha Sandip Yadav, 19, India
34. Ofek Adir, 19, Israel
35. Barbara Pozzobon, 31, Italy
36. Ginevra Taddeucci, 28, Italy
37. Airi Ebina, 23, Japan
38. Ichika Kajimoto, 21, Japan
39. Mariya Fedotova, 26, Kazakhstan
40. Darya Pushko, 21, Kazakhstan
41. Jiyeon Hwang, 18, South Korea
42. Sueah Kim, 18, South Korea
43. Malak Meqdar, 18, Morocco
44. Paulina Alanis Hernandez, 20, Mexico
45. Sharon Guerrero Cho, 19, Mexico
46. Lisa Pou, 26, Monaco
47. Micheline Gabrielle Bathfield, 19, Mauritius
48. Margarita Ershova, 19, Neutral Athletes B
49. Ekaterina Sorokina, 24, Neutral Athletes B
50. Cielo Peralta, 18, Paraguay
51. Maria Fernanda Arellanos, 16, Peru
52. Klaudia Tarasiewicz, 21, Poland
53. Mafalda Rosa, 21, Portugal
54. Alondra Itzel Quiles, 20, Puerto Rico
55. Callan Lotter, 19, South Africa
56. Catherine van Rensburg, 21, South Africa
57. Li-Shan Chantal Liew, 26, Singapore
58. Kate Ona, 17, Singapore
59. Spela Perse, 28, Slovakia
60. Chonpasanop Chatwuti, 14, Thailand
61. Kamonchanok Kwanmuang, 20, Thailand
62. Jia-Shien Lin, 17, Chinese Taipei
63. Yu-Wen Teng, 28, Chinese Taipei
64. Su Inal, 15, Turkey
65. Pilar Canedo, 21, Uruguay
66. Mariah Denigan, 22, USA
67. Brinkleigh Hansen, 15, USA
68. Ruthseli Guadalupe Aponte Teran, 26, Venezuela
69. Daniela Chinquinquira Suarez Correa, 16, Venezuela

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