Since 2005. The Arizona Lymphomathon is a non- competitive 5K family-friendly walk at the Phoenix Zoo. Register on-line and start your personal fundraising with a $25 minimum donation. The minimum donation is not mandatory for children (17 years of age and under). Each walker will receive a Lymphomathon t- shirt and wrist band to enjoy all day admittance at the Phoenix Zoo. The event is in support of the fight against lymphoma.