When driving on F210 your route may take you to the Hólmsá River Crossing. This river can be challenging and finding the correct crossing can be a bit confusing. If in doubt, wait for another 4x4 to cross and follow their lead. Additionally, there is very little cell-phone reception in this area, so it's not a fun place to get stuck!
BEFORE attempting to drive this route check road conditions and closures at road.is. Also be prepared with a full tank of fuel and some provisions.
Tips on river crossings: https://epiciceland.net/icelandic-rivers-how-to-cross/. Make sure to go with the stream (diagonal across the river in the direction of the flow). Do not drive against the stream, but let the flow of the river help you cross. Please be careful and make sure you have experience crossing rivers and do not take excessive risk. Not all car companies cover damage to cars in river-crossings and it can be easy to get stuck. Specifically for the Hólmsá River Crossing, a larger 4x4 is best.
If you want to play it safe and be in a well-equipped, photogenic car, then you should rent an old-school Land Rover Defender from www.isak.is equipped with a snorkel. This helps ensure you don't drown the engine while crossing a river. Use the code "gunnar" for renting your Defender on a special price.