SMA ACFT ON FLOATS HIT A ROCK ON TKOF.

Narrative

LANDED ON ALPINE LAKE AS PART OF A REGULAR FEATURE OF A SIGHTSEEING FLT IN WILDERNESS AREA. DURING SUBSEQUENT TKOF; STRUCK A ROCK AND DAMAGED BOTH FLOATS WHICH BEGAN TAKING ON WATER. TAXIED TO SHORE; DISCHARGED PAX ( NO INJURIES) AND SECURED ACFT. ACFT REMAINED AFLOAT. THIS LAKE IS A LARGE; DEEP LAKE THAT SEES REGULAR ACTIVITY FROM SIMILAR AIR TAXI OPS. I HAD OPERATED FROM THIS LAKE BEFORE AND WATCHED SIMILAR ACTIVITY WITHOUT EVER OBSERVING THE ROCK OR BEING WARNED OF ITS PRESENCE. I WAS THEREBY LULLED INTO THE BELIEF THAT IT WAS A LAKE WITHOUT OBSTACLES AND DID NOT OVERFLY TO CHK THE AREA I WOULD BE OPERATING IN; AS I WOULD DO WITH ANY AREA THAT WAS NEW TO ME. THERE WAS STILL THE OPPORTUNITY TO SEE THE ROCK DURING THE APCH AND LNDG OR BEFORE I BEGAN THE TKOF. I BELIEVE THAT WAS MISSED BECAUSE THE ROCK ONLY EXTENDED 3- 4 INCHES ABOVE THE SURFACE AND THE SURFACE WAS RIPPLED WITH 3-5 KTS OF WIND; MAKING THE ROCK INDISTINGUISHABLE. IF THE SURFACE WAS CALM OR THE WAVES BREAKING OVER IT; IT MAY HAVE BEEN MORE APPARENT. AN OVERFLT SHOULD HAVE DETECTED THE ROCK; HOWEVER; THESE FLTS ARE TIME LIMITED AND ONE OF THE REASONS FOR OPERATING FROM A FAMILIAR AREA IS TO PRECLUDE THIS STEP. OBVIOUSLY; THE TIME SAVED IS NOT WORTH IT.