Bogs are areas of still water, sometimes with peat or mud, and it is difficult to ascertain when approaching them how deep they are. Be prepared for anything. You may go in up to your axel, come to a stop, and then have to stick your foot out and get it soaked. We have been in bogs where, once you put your foot down, you pull it out and your boot gets sucked right off of your foot! Some bog areas will have boardwalks built over them to facilitate crossing. Use them. Be prepared to pedal real hard in a bog, and expend quite a bit of energy for the length of ground covered.