When I was there more than 20 years ago, you could get away without a bulletproof vest. Nowadays, I'm not so sure…
Sonamarg means something like "the meadow of gold." It's a little less than 100km from Srinagar, the capital of Kashmir. Best way to get there is to hire a cab for the day. The drive will take several hours.
The valley itself is pretty but the fun part is trekking up onto the glaciers. The view of the surrounding mountains is breathtaking.