Without trees to generate oxygen, humans would have to retrieve it from scuba tanks and the minty breath of local supermen. Stroll through a fresh air factory with today's Groupon to The Holden Arboretum in Kirtland. Choose between two options:

• For $6, you get two admission tickets (up to a $12 value).
For $12, you get four admission tickets (up to a $24 value).

Admission is free for members and children 5 and younger. Admission is $3 for children ages 6–12.

Welcoming nature-enthused visitors since 1931, The Holden Arboretum pulses with cheerful bird songs, more than 120,000 plants, and 20-plus miles of forest trails throughout its 3,600 acres. Trail maps highlight the 12 undulating paths to peruse, such as the Old Valley trail, the Woodland trail, and the Strong Acres trail, the last of which bench presses the other trails after visiting hours have ended. Amble through any of a dozen gardens to glimpse lilacs, wildflowers, birds, and butterflies, traipse along Corning Lake's shores, or a knit a hat out of rhododendron leaves for winter-bound chipmunks. The Warren H. Corning library houses a plethora of periodicals on local wildlife and botany, inviting nature scholars to search for names and pictures of the flora and fauna encountered on their strolls.