A 41-year-old Sausalito woman died Tuesday on the start of a three-day rafting trip with her husband when they hit unexpectedly fast rapids on the Tuolumne River, a Tuolumne County Sheriff's sergeant said.

Around 1:30 p.m. Mariati Tani, her husband, two other family members and a river guide were rafting down the river when the raft encountered an unexpected Class 5 rapid and became lodged on a rock, sheriff's Sgt. Jeff Wilson said.

Most of the party was ejected from the raft and Tani became pinned under the water and raft. She was submerged for 10 minutes before the guide could free her, Wilson said.

She was pronounced dead after 30 minutes of CPR efforts could not revive her. A California High Patrol helicopter was called in to bring her and her husband to Pine Mountain Lake Airport in Groveland where they met with sheriff's officials, Wilson said.

According to Wilson, river water levels fluctuate and are unpredictable. Class 4 rapids are usually found along the rafting route, he said.

"You normally don't see that type of condition," Wilson said.

Wilson said the rafting companies work hard to host successful trips, but, "Let's face it, it's dangerous," he said.

Tani's husband had been on several previous rafting trips and this was the first day of the family's three-day trip down the river, Wilson said.