WHILE ON A VFR FLT FROM SKAGWAY TO JUNEAU, AK, THE PILOT ENCOUNTERED OBSCURING WX CONDITIONS AND REVERSED COURSE. EN ROUTE BACK TO SKAGWAY, HE ENCOUNTERED LOW CEILING, RAIN AND FOG. HE DESCENDED TO FLY UNDER THE WX AND LOST VISUAL REFERENCE AT ABOUT 150 FT ABOVE A SALTWATER INLET. HE INITIATED A CLIMB IN IMC, BUT THE ACFT IMPACTED ON A STEEP, WOODED HILLSIDE.