wear sturdy, close-toed shoes; sunscreen; and a hat (lava fields are often without shade). bring lots of water; at least a quart per person. long pants are a good idea. they'll protect you from the sun and lessen the severity of abrasions should you fall.
avoid cliffs, cracks in the earth, and steam vents. they can be unstable, slippery, or both.
heed signs warning of volcanic fumes. people with heart or respiratory problems, infants, children, and pregnant women are particularly at risk. if the lava is flowing into the sea, avoid the steam plumes. the chemistry of lava plus seawater produces hydrochloric acid, which can sting the eyes and throat, and present a potentially lethal situation for those with respiratory problems.
what you should know
for updates on current volcanic activity in hawaii volcanoes national park, call (808) 985-6000; visit www.nps.gov/havo/home.htm for park info.
if you go at night, a flashlight is a must. few places are darker than a lava field at night.
most people view the lava at sunset; sunrise provides the same negligible light for ideal viewing, with far fewer people.
from crater rim drive, chain of craters road is a 40-mile round trip. top off your tank before you enter the park. there's a motor-home-cum-visitor-center near the end of the road (allowing the park service to be where the flow is).
get out of the car. there are more than 150 miles of trails in the park, and they offer far more than just lava - lush rain forest, hawaiian petroglyphs, walk-through lava tubes, and breathtaking seascapes. for a great off-the-beaten-path treat, hike the mauna ulu trail near hilina pali road.