Is it a sentence or a sentence fragment?

1. At first her boat drifted calmly through the Grand Canyon.

2. Then the river dropped suddenly.

3. And became foaming rapids full of dangerous boulders.

4. Many of which can break a boat.

5. Michelle's boat was small.

6. With one guide and four passengers.

7. Some passengers prefer large inflatable boats with outboard
motors.

8. Carrying eighteen people.