Lake Serene
Lake · Washington
ℹ️ Community-reported spot. Details below are compiled from public sources and are reported to be accurate — always verify locally before visiting.
About this swimming hole
An alpine lake at the base of Mount Index's granite walls, earned after a steep five-mile climb with cables and ladders near the top. The reward is a cold, pristine swim with almost nobody else around.
Good to know
| Water type | Lake |
|---|---|
| Water temperature | 50-55 in summer |
| Best season | July-August |
| Fees | NW Forest Pass |
| Reservations required | No |
| Hours | daylight hours |
| Parking | Lake Serene trailhead lot; fills early |
| County | Snohomish County |
| Nearest town | Index |
| Safety notes | no lifeguard; strenuous hike; very cold water |
Map
Nearby swimming holes
Frequently asked questions
Does Lake Serene require reservations?
No reservations are required at Lake Serene based on current information — but verify before you go.
Is there a fee to visit Lake Serene?
Reported fee info: NW Forest Pass. Fees can change — confirm with the official link.
When is the best time to visit Lake Serene?
The best season is typically July-August.
⚠️ Verify before you go. Conditions, fees, reservations, and access can change — confirm details with the official link before visiting. Last verified: September 2026