Tough Mudder returns to Northstar on July 13-14 and Sept. 28-29.

Tough Mudder events are 10-plus mile obstacle courses designed by British Special Forces to test all-around strength, stamina, mental grit and camaraderie. Tough Mudder’s courses have attracted 750,000 participants worldwide to date. Through Tough Mudder, these participants have raised more than $5 million for the Wounded Warrior Project.

Registration is open, with the summer event 77 percent sold. Rates for the summer and fall events are scheduled to increase May 3.

Spectator tickets will be available for sale online for $20 until noon on the Friday before the event weekends. They will be sold for $40 cash only onsite. Dogs are not permitted.

For more information about the Tough Mudder events at Northstar or to register to participate, go online.