Free. Tours are limited to 10 persons per tour guide on a first-come, first-served basis; arrive 30 minutes before tour departure.
$1 an hour (maximum of $5 a day).
Daily dawn-dusk. Tours are given daily at 9:30 and 1:30, Jan.-Mar.; daily at 9:30 in Apr. and Nov.-Dec.; Wed. at 9:30 and fourth Sat. of the month at 9:30, rest of year. Interpretive center open Tues.-Sun. 10-4; closed major holidays. Allow 1 hour minimum.