A Class 5 rapid, the largest you can get, is defined by Wikipedia as follows:
“Whitewater, large waves, continuous rapids, large rocks and hazards, maybe a large drop, precise maneuvering. Often characterized by “must make” moves, i.e. failure to execute a specific maneuver at a specific point may result in serious injury or death. Class 5 is sometimes expanded to Class 5+ that describes the most extreme, runnable rapids (Skill Level: Expert)“
On the day we went down, Río Suárez (class 4/5) was at the maximum water level in which rafting is still possible. In fact, we had to delay a few hours to let the level drop a bit.
Thankfully our guides were members of the Colombian national team, highly experienced and knowledgable. One guide sat at the back of the main boat with oars, the other in a kayak ready to rescue fallen rafters.
We were doing really well up until the last class 5 rapid called “The Surprise”, where things went a little awry - the boat hit a massive wave and shot upwards at a nearly vertical angle, causing the two big guys in the front to fall backwards sweeping us all off into the water. Simon and I managed to hold the side ropes and pull ourselves back in, but the rest were held down before floating away downstream.
Luckily it was the last rapid, and within 10 minutes we’d rescued everyone and collected the paddles. A couple of bruises and a lot of swallowed river water, but overall an excellent experience.