In summer you can drive Blue Lakes road (No. 850) past Lower Blue Lake to just below the dam at Upper Blue Lake. The road is rough but passable for 2WD when dry. From there, a trail loops around the lake. It is not maintained and tricky to follow in some places because of steep slopes and loose surface, but still negotiable. Note that when the lake is completely full, however, hiking the shoreline might not be feasible everywhere. More paths link the two Blue Lakes, upper and lower. A series of waterfalls tumble in between them, among rocky meadows that bloom with wildflowers in summer. There is a smaller parking area along a 4WD road at the lower lake as well.

Sources: https://www.alltrails.com/explore/trail/us/colorado/blue-lakes-trail--2 https://www.gobreck.com/trip-ideas/hiking/moderate-hiking-trails-in-breckenridge/ https://www.outdoorproject.com/adventures/colorado/hikes/blue-lakes-trail