Families, friends and corporate groups will flood the CBD and Northbridge in teams of up to six for the treasure hunt, using the Ramble app to reach well-known and secret Perth checkpoints in a bid to win prizes including a trip to Europe.
The trip goes to the team with the highest score, and there are prizes for the best team costumes.
The first Ramble raised $40,000, the second $75,000 and this year’s aims for $150,000.
All proceeds go towards medical research, with recipients including Telethon, the Southern River-based Amanda Young Foundation and Australian Rotary Health.
The event runs 11am-3pm at Russell Square in Northbridge, with winners announced 4pm.
Register for $99 per family or $160 per adult team at www.rotaryramble.com.