AFTER DEPARTING THE GUSTAVUS ARPT, THE PLT TURNED THE ACFT TOWARD EXCURSION INLET & AIR-FILED A VFR FLT PLAN. AFTER THE FLT PLAN WAS FILED, THERE WERE NO FURTHER RADIO TRANSMISSIONS FROM THE ACFT. A SEARCH WAS INITIATED, BUT HVY FOG, CLOUDS & DARKNESS HAMPERED THE SEARCH. WRECKAGE WAS FOUND THE NEXT MORNING, WHERE THE ACFT HAD CRASHED ON STEEP RISING TERRAIN IN A BOX CANYON AREA. IMPACT OCCURRED AT THE END OF A VALLEY THAT BEGAN NEAR EXCURSION INLET. ELEVATION OF THE CRASH SITE WAS APRX 4000 FT, TERRAIN IN THAT AREA ROSE TO ABOUT 4600 FT. TWO OTHER PILOTS THAT DEPARTED HAINES NEAR THE TIME OF THE ACDNT RPRTD THE CEILING WAS BROKEN TO OVERCAST AT ABOUT 4000 FT. RPRTDLY, THE MOUNTAIN TOPS WERE OBSCURED, BUT THE VISIBILITY BELOW THE CLOUDS WAS ABOUT 20 MI. THE PROP BLADES WERE FOUND WITH DEEP CHORDWISE SCARS & LEADING EDGE/ROTATIONAL DAMAGE.