The Millinocket Marathon & Half and the Mount Desert Island Marathon, Half & Relay are pleased to once again join forces to produce the popular Sea to Summit Maine Race Series, featuring two of our great state’s marquee events and a very special finishers medallion!

When you sign up for MDI and select ‘Sea To Summit’ you are automatically signed up for Millinocket and race series! Click HERE to learn more.

Reminder: Everyone that signed up for the 2020 Sea to Summit Series was issued a $12 refund on October 7th, including those that deferred their MDI registration to 2021. If you would like to participate in the series this year, you will need to re-register. Please follow the directions on the Run MDI FAQ page to update your registration. Thank you!