Occasionally you may need to transport a pet red-eared slider turtle by vehicle (for example, during a move). This can be a very stressful time with turtles, but with some planning and preparation, the move can go quite smoothly.
For travel in the car, your turtle can be placed in a plastic box such as a storage container. Holes can be drilled in the lid of such a box for ventilation, but you will want something that closes securely since turtles can be adept at escaping. Place a good layer of padding in the bottom of the box, such as a towel (but avoid any with loose threads or loops that could entangle the turtle's claws), paper towels or newspaper. The box should have a bit of space for the turtle, but don't give the turtle lots of room to move around (the goal is to pad the turtle well and make him or her very secure).
What About Water?
Even semi-aquatic turtles such as red-eared sliders can handle being out of the water for quite a while. For extended trips, you may choose to mist the turtle and or dampen the padding at the bottom, but keep in mind this will be cooling to the turtle so only do this if you can keep the turtle warm enough. For trips of a few hours, your red-eared slider will be fine if kept dry. However, on longer trips, you might want to provide a large water dish shallowly filled with water and take a break to refill it and offer your turtle some time to drink of get into the water dish itself.
This will be your biggest challenge, though typically overheating is probably more of a concern that being too cool (though a cold turtle will be sluggish and can be predisposed to developing illnesses). Use a thermometer on the turtle's box or get a temperature gun to monitor the temperatures. If you are traveling in warm weather, there are a few alternatives. You can regularly mist your turtle or keep the padding damp; evaporation of this water will be cooling. If your car has air conditioning, you can use this to keep the car cool, being careful not to let the turtle get too cool (and don't put the turtle in front of an air vent). You can also place the turtle's box inside a cooler (the styrofoam ones work well for this- keep the top open for aeration) and add a wrapped cool pack to the cooler. Never put an ice pack or cool pack directly in the turtle's box—keep the cool pack separated from the turtle itself.
In cooler weather, you may need to use a warming pack in much the same way. Place the turtle in its box inside a cooler, and add a wrapped heat pack (a bottle of hot water, a microwaved potatoe, a sock with heated rice, or a heating pad set on low (if you have a plug-in) for longer trips). Again, never let the turtle come in direct contact with the hot pack.
If you have drilled some holes in your box for ventilation, your turtle will probably be fine. However, especially for longer trips, you may want to open up the box periodically to let in some fresh air. Throughout long trips, periodically check that no mold or fungus is growing in your pets' container, especially because they are living in a damp environment.
Since turtles, dependent on age of your animal, may be able to go a few days without food, you can feed your turtle prior to the trip to ensure they are eating, and then see how their appetite is throughout the trip. Two to three days of not eating in an adult red-eared slider is a normal feeding schedule gap, so if they don't eat during the trip, it isn't a big deal—as long as they eat again when you are at your final destination. Juveniles or hatchlings need to be fed daily, regardless of travel.
Overnighting in Hotels
If you need to stop overnight, make arrangements well ahead of time and make sure you get permission to keep your turtle in your room. Bring a medium-sized plastic storage tub—you can set this inside the bathtub and give your turtle some warm water to swim in. Be courteous to the cleaning staff and other guests by not putting your turtle directly in the tub or sink or letting it roam around the room (due to the risk of contaminating surfaces with Salmonella bacteria). When you pack your turtle back up in the morning, simply dump the turtle's water down the toilet. To be extra courteous, wipe down the bathroom surfaces and anywhere else the turtle may have had contact with anti-bacterial wipes.