Online registration is now OPen!

On-site registration will be open on Saturday, 3/2 from 10:00 am - 5:00 pm, and race day starting at 6:00 am if space is available.

If possible, come on Saturday to avoid the race day rush.

All registrations are final and non-refundable, no exceptions.
Registration fees cover costs of hosting the 2019 Treeathlon and support the Stanford University Triathlon Team.


draft-legal sprint & F1

Registration for the draft-legal race is now open to Junior Elite, Collegiate, and Elite athletes as well as experienced Age Group athletes (with permission). Experienced age groupers who would like to participate should contact the race director at to get a registration code.


Classic sprint

The Classic Treeathlon is a popular event, so we recommend that you register early. Registration will be capped at 650.