The best place to wander under giant redwoods in the East Bay! The stream trail is beautiful and accessible, and there are many other amazing trails to hike and run. This has been my go to trail running spot since moving to Oakland 7 years ago.
Reinhardt Redwood Regional Park
Lake Merritt is great, but if you really want to immerse yourself in nature in the middle of Oakland, then this is the spot. There's a bonsai garden, sensory garden, rare plants, and more in a really serence setting in Lake Merritt.
The Gardens at Lake Merritt
This has been my go to place to run/walk during the day in Oakland for many years. It's about 3 miles around.