What should you leave with a friend or relative before a long outing on the water?

The one that you should do when you leave with a friend or relative before a long outing on the water would be: Float plan for your trip 
Whenever you plan to do an outing on the water, you need to notify some sort of guard within the territory and inform them about your activities. By doing this, they will be notified if somehow you're not coming back to the land because of some problems. This precaution is known as a float plan