We study the political effects of interethnic contact in a public social space that has become increasingly politicized in multiethnic democracies: swimming pools. Our empirical analysis combines granular information on the geolocation of all public pools in Germany with high-frequency panel survey data on the electoral preferences of more than 240,000 voters. We leverage the seasonality of outdoor swimming pools for causal identification in a difference-in-differences framework. Our results indicate that interethnic contact in public pools increases far-right voting by about 0.8 percentage points. This effect is only present in localities with high levels of ethnic diversity. Through additional analyses of precinct-level electoral returns, we demonstrate that these effects translate into electoral gains for the far-right. Our findings shed new light on the conditions under which intergroup contact not only fails to reduce but fosters racial prejudice and anti-immigrant sentiment.