The Mammoth Half Marathon is a premier race event and the 2nd leg of the San Diego – Mammoth Challenge. The race is organized by the San Diego Half Marathon team. The San Diego Half Marathon is a nonprofit 501(c)(3). 100% of the net proceeds from the Mammoth Half Marathon & 5K event will go towards community service projects and select charitable causes in Mammoth Lakes. In addition to the funding, we hope to catalyze volunteerism as a way to help the communities throughout Mammoth Lakes. The Mammoth Half Marathon will also benefit additional charities by enabling runners to raise money for any or all of the select causes that are important to them.