Went up Back Creek, Bald Ridge, North Peak as recommended by the ranger at the bottom. (Two accompanying 18-yr-olds took Eagle Peak and went a mile farther.)  Loose dirt and rock trails, moderately steep climbs with higher heart rates than Tam. 4.5 hours up, 6.5 miles, 2+ liters. Spent an hour at the top for lunch, visitor center, photos with fog in the background. Ice cream and cold drinks sold at the summit and water available. Trail shoes and poles really helped with first half down which was steep. Last half was fire road and exposed. 3.5 hours down, 7+ miles, 1.75 liters. A few mountain bikers and more hikers on trail than going up. Picked this day since forecast was unseasonably cool at 68-72. Higher 70s in areas with no breeze. Good day for Diablo.