Seetawaka Botanical Garden, Botanical garden in Avissawella, Sri Lanka.

Seethawaka Botanical Garden covers 42 hectares (105 acres) beside the Indikada Mukalana Forest Reserve at Illukowita, Avissawella. A stream runs through the grounds, and the tree cover is dominated by large Terminalia arjuna trees. The garden holds wet-zone plant collections and bamboo, with lawns sloping to a pond.

The land was a rubber and tea plantation called Pannaagula in the 20th century, but much of it was abandoned and later taken over by the Land Reform Commission. Construction of the botanical garden began in 2008, and it opened to the public in October 2014 as Sri Lanka's most recently built botanical garden.

The garden holds significance as a center for protecting plant species found in Sri Lanka's wet regions, showing visitors which plants naturally thrive in this climate. Walking through it helps people understand how these plants support the local environment and why their preservation matters today.

The garden lies around 49 kilometers from Colombo and is accessible via the Puwakpitiya-Thummodara road near Illukowita. Visitors should plan for about four to five hours to explore the entire grounds.

A natural stream runs through the grounds, creating special conditions for plants that thrive in wet environments. The large Terminalia trees shape the microclimate and give the garden its distinctive character.