The 21st annual Whidbey Island Triathlon returns Saturday, July 29, which means certain roads on the South End will be either closed or restricted.

The road closures are to ensure the safety of runners and cyclists as they trek through the scenic route that offers views of Saratoga Passage and the Cascades. South Whidbey Parks and Recreation District estimate 300 athletes will participate.

The road restrictions are as follows:

• 7:30 – 9:15 a.m.: Lakeside Drive between Traverse Road and Pintail Road will be limited to one lane, and no street parking is permitted.

• 9:15 — 11:15 a.m.: Traverse Road and Lakeside Drive will be closed.

• 9:30 a.m. — 12 p.m.: De Bruyn Avenue between Saratoga Road and Third Street will be closed.

• 9:30 a.m. — 12 p.m.: Second Street between Park Avenue and De Bruyn Avenue will be closed.

• 9:45 a.m. — 12 p.m.: Turns from Bayview Road onto Andreason Road will be limited.

Drivers are also expected to encounter runners and cyclists from 9:30 a.m. to 1:30 p.m. on roads across the Langley area. Organizers ask drivers to exercise “extreme caution” along these routes.

The parks district is also seeking additional volunteer manpower for the triathlon. Over two days, the district estimates it will need to fill over 100 volunteer positions.

For more information on volunteering, email programs@whidbey.com or call 360-221-6788. To sign up for a volunteer spot, visit http://signup.com/go/WuRMNaT.