The initial route was dug through a highly unstable area of glacial fill, making it extremely treacherous.

Molten pools of lava made a slip extremely treacherous.

The rain made the path she took extremely treacherous.

Based on the reconnaissance photos, they had all known that the landing would be extremely treacherous.

Given the atrocious landings and the fact that the rock is extremely treacherous when wet, many climbs are very bold.

Health officials say the dump site is extremely treacherous.

Another issue that they need to be aware of is tule fog, which can make driving in the San Joaquin valley extremely treacherous.

"This is an extremely treacherous environment for forecasting," Mr. Forsythe said.

The weather was extremely treacherous with high winds, small craft warnings, and pounding waves on the shoreline.

The climb of the sloping roof was extremely treacherous.