Come learn all about Trailhead!
You’ll get an introduction to the Trailhead learning platform, hands-on experience while you earn badges, and of course, awesome swag!
More info- https://developer.salesforce.com/blogs/developer-relations/2015/06/join-us-summer-trailhead.html
** IMPORTANT **
Do bring laptop with full charge and arrange for internet (data card/dongle, tethering, etc.). There will be hands-on fun.