Babies and toddlers are the easiest children to shepherd safely outdoors, because they are incapable of moving fast enough to get into too much trouble on their own. However, because tears are their only way of communicating discomfort, it's important to keep a watchful eye out for the maladies to which they are most susceptible: hypothermia, heat illness, altitude sickness, and especially infection. Children suffer approximately twice the number of infections as adults (earaches are common), and because they may not have built up antibodies, their reactions tend to be more severe. Also, their narrow respiratory passages prolong and exacerbate infections. Know what antibiotics your child may be allergic to and bring precautionary medications with you if you will be far from medical help.