Independent routes through Halong (not Catba)

Hi. I visited Catba 11 years ago by tour. It was touristy then, so I don't want to go back now.

However, the other islands in the area look great. What's the deal with these?

I suppose it's possible to get a bus over to Haiphong or nearby and get boats out. Has anyone done this WITHOUT BEING ON A !(@*#*!@#!@ TOUR and what was your experience?

Bearing in mind the weather now is foggy and slightly cold, multi-day jungle hikes across remote mountains are out, but ideally some exposure to both island forest and coastal scenery would be ideal. A quiet place to stay on an island away from hustle and bustle would be gold.

Cheers.