The hotter it gets, the softer it gets. The sun can make the dunes treacherous.
Teams of quads are also fierce competitors in the Gazelle Rally.
Navigators also function as spotters. Here the US Nomads team pick their way through sharp rocks.
The truly hard-core women compete on motorcycles. Think you could do nine days in the Sahara on a moto?
In 2013 we competed in the Rallye Aicha des Gazelles in an Isuzu D-Max. Here navigator Sabrina is taking a heading. Navigators must exit the truck to take accurate headings, as any nearby metal will alter the compass reading.
Competitors can choose to go around obstacles, like dunes, but will incur a penalty. The difference between the actual distance traveled and the straight-line distance is the penalty.
We ended up on the top of this mountain, absolutely sure we would see the flag on the other side. We we wrong -- so very, very wrong -- but at least we had a good place for lunch.
A moment that Sabrina and I will remember forever. We were digging out of some camel grass when this girl came out of the desert like a vision. I have no idea where she came from or how she got to us. We didn't have a common language, but we gave her some food and water and she allowed us to take this photo of her.
While I changed a tire, Sabrina looked at her maps for the next checkpoint.
A navigator's dashboard: pencils, rulers, Terratrip and the French dessert Yabon. It's Ya-licious!
The plotter ruler is integral to finding the heading and distance on a map.
The two women on the right are one of the top teams, but they still took the time to help us. The Gazelle Rally is unlike any other in that cooperation is not only expected, it's required.
At the end of a long day, teams return to the bivouac where they can grab a hot shower and meal. Friends and family members can email their Gazelles and there are a few computers for competitors to use.
There is even a bar in the bivouac, but with a 4 a.m. wake-up call -- and anywhere from eight to 16 hours of driving per day -- most Gazelles prefer to turn in early.
Our truck in 2014 was also an Isuzu D-Max. It's too bad these trucks are not available in the US, as it was a good little rig. The four-cylinder turbo diesel had great torque and the lighter weight made it a natural in the dunes.
Even though Sabrina has the last word on all navigational decisions, we still worked together to find our heading.
We were constantly airing our tires up or down depending on terrain.
The locals are always happy to lend a hand. Here American Team X-Elles showed some kids how it's done.
The ceremonial finish on the beach in Essaouira is a highlight. Finally time for a real shower!
During the two days of dune checkpoints, Gazelles can choose between easy, moderate or expert level dunes. American sisters Susannah and Jo Hannah Hoehn are seen here in expert level dunes.