In anime that aim for a more "natural" look (black and brown hair only), the characters with the lighter hair will be rebels, fashionistas, foreigners, or spending a lot of time in the water (surfer or swimmer). This trope is about the latter. Some works play it subtly, darker than average skin with lighter than normal hair, while cartoonier works might go for the more visually striking Dark-Skinned Blond. There is some crossover with ganguros, who are sometimes perceived as "beach bunnies", but the light-haired swimmer is generally more interested in sports than in hitting on people at the pool.
Also note that if the show is inhabited by characters with a rainbow of different hair colors, it's not an aversion if a non-swimmer has lighter-colored hair than a swimmer, especially since light hair has plenty of other connotations as well.
A variation of this in Caucasians would be slightly green-tinted hair in blondes.
Truth in Television. Salt water/chlorine and excessive exposure to sunlight can cause black hair to get sun-bleached to brown, as well as making it dry and brittle. This is partly why the dark-haired part of Raven Hair, Ivory Skin was once so valued in Asia: It's associated with the rich, whose hair was mostly untouched by harsh sunlight, as opposed to the peasants with brown hair. Of course, getting blond hair from simply swimming is stretching it.
- Shinichi Maki of Slam Dunk has light brown hair and dark skin from surfing.
- In the one-shot Piercing, it's revealed Ryota Miyagi spent his childhood near the ocean. Is it any wonder why he has brown hair and tan skin?
- Momo from Peach Girl is mistaken for a ganguro, but she's really this.
- Mizumachi of Eyeshield 21 has the extreme blonde hair-tan skin varient, which provides a nice visual contrast to the raven hair ivory skinned Kakei.
- Kagura of Azumanga Daioh, though curiously not as brown as Yomi's.
- Averted in Kenko Zenrakei Suieibu Umisho, which is about a high school swimming club and has a large variety of hair colors, both light and dark.
- Ditto with Free!.
- The World God Only Knows: One of Keima's conquests had hair that turned light brown and unmanageable after being on the swim team for so long.
- Averted in Rumbling Hearts, where the Olympic-level swimmer Mitsuki has dark blue hair. Then played straight after Mitsuki ends up quitting due to a certain accident she accidentally caused. Her successor, Akane, has light orange hair.
- The victim of the accident is Akane's older sister, Mitsuki's best friend, and has light brown hair throughout. It's not obvious but Mitsuki's hair goes from blue to a slightly darker bluish-purple after the accident.
- Discussed in Lucky Star, which doesn't make much sense given that most of the cast has candy-coloured hair and only one character in the entire cast even has black hair.
- In Pokémon, Misty has red hair. The other main characters who do not swim have brown or black hair.
- In Code Geass, averted as the swim club includes many hair colors. However, Shirley is the lighter - haired of the main characters with red hair, and the coach is a Dark-Skinned Blond.
- In Rosario + Vampire, Tamao Ichinose (who is actually a mermaid) is the president of the swim club; in the manga she has dark hair, but in the anime her hair is light green. This (dark hair in manga, lighter hair in anime) seems to hold true for most of the mermaids in the series.
- Inverted in Mahou Sensei Negima!. Akira Ookochi is a swimmer, but she is actually raven hair ivory skinned.
- Of all three Riders in Kamen Rider Agito, Ryou Ashihara (Kamen Rider Gills) has the lighest hair, since he used to be a college competitive swimmer before the whole plot started.
- Half of Final Fantasy X's human playable cast are brunettes (Yuna, Lulu, and Auron), the other half consisting of two blondes (Tidus and Rikku) and a redhead (Wakka). Only the latter half of the team can swim and fight underwater.
- Toyed with in Danganronpa: Trigger Happy Havoc: the super Highschool Level Swimmer Aoi is tanned, but her hair is a normal shade of brown.
- Toyed with in Tokimeki Memorial 1: potential love interest Nozomi Kiyokawa is a Bokukko swimmer... with GREEN hair