Keji's Backyard Ultra is an annual endurance running event held in the scenic Kejimkujik National Park and National Historic Site in Nova Scotia, Canada. The 2025 event marks the fourth edition, featuring a unique backyard ultra format where participants run a 6.67 km out-and-back loop every hour starting at 9:00 AM and must complete each loop within the hour to continue.

The course follows the Mersey River on a relatively easy gravel trail with minimal elevation gain, combining camaraderie, endurance, and natural beauty. The race continues until only one runner remains able to complete the loop within the time limit.

- Unique backyard ultra format: run 6.67 km loops every hour until only one runner remains
- Scenic, relatively easy gravel trail along the Mersey River
- Capped at 150 participants
- Current record: 54 loops held by Lee Murphy
- Prize money: $2000 for winner, $1000 for assist, $500 for top female