Whiteface and Esther
Whiteface and Esther is the Adirondack High Peaks double-day line that links Whiteface Mountain and Esther Mountain from the Wilmington, NY area. The route is done as a day hike, with Esther typically treated as a side trip off the main climbing line to Whiteface.
A common itinerary starts at the Atmospheric Sciences Research Center trailhead off NY 431 and then uses the Marble Mountain trail to gain elevation before switching to the Wilmington Trail for the push toward both peaks.
On the way up Marble Mountain, expect a steep climb early in the hike and then a transition to the ridgeline network that feeds into the Wilmington Trail. The Marble Mountain-to-Wilmington connection is where you commit to continuing on toward Esther/Whiteface rather than turning back toward the lower trail network.
As you work up Wilmington Trail, you reach a junction where you can leave the main line for Esther. The Esther spur is described as a short, heavily wooded herd path that climbs to the Esther summit from the junction.
After tagging Esther, you return to the junction and continue on toward Whiteface. Near Whiteface, the route crosses the Whiteface Veterans Memorial Highway and then finishes with a short rock scramble and an exposed ridge approach to the summit.
The Whiteface summit is reached via the Stairway Ridge style approach (steps/zigzags through alpine terrain) and ends at the bare summit area. Whiteface is also notable for being reachable by road to near the summit via the Veterans Memorial Highway, which affects how crowded the top area can get.
More information: Wikipedia, Esther and Whiteface via Marble Mountain - dismal wilderness, Hike Whiteface Mountain and Esther via Marble Mountain