Cell service is nonexistent in many parts of Rocky Mountain National Park. Download maps and reservations before you enter, carry a paper map, and tell someone your plan.

Estes Park sits near 7,500 feet and the trails climb from there. Altitude sickness can affect anyone above 8,000 feet. How to plan a first day that keeps you out of trouble.

Afternoon thunderstorms are common in summer in Rocky Mountain National Park, and lightning above treeline is the real danger. Start early, watch the sky, and plan to be below treeline by early afternoon.