The tunnels were dug with simple tools and bare hands during the French occupation in the 1940s, and further expanded during the Vietnam War in the 1960s to provide refuge and a defensive advantage over the American soldiers. Despite all the bombings in their town, the Cu Chi people were able to continue their lives beneath the soil, where they slept, ate, planned attacks, healed their sick, and taught their young. Some even wed and gave birth underground, but over 10,000 lost their lives here.
A multitude of tour buses leave Ho Chi Minh City for the Cu Chi tunnels daily. Expect to pay around US$5 for a half day guided trip (not including admission to the tunnels), with 90 minutes travel and about an hour and a half touring the area. Buses mostly leave around 8:00, so consider a private car if this isn't suitable. Tour operators on Phan Dinh Phung will quote from $35 - $50 return by private car, or possibly lower -- don't be afraid to shop around.
If you're making the trip independently, hop on bus 13 from the Ben Thanh bus station. The last stop on the route is Cu Chi. Bus fare is 5,000 VND, and the ride is about 1.5 hours. When you arrive at the Cu Chi bus station negotiate a motorbike driver for the 20-minute ride for around 100,000 VND return (pay attention as starting price could be 200,000 VND or more). It could also possible to take bus 79 but not really sure if it stops near Ben Duoc entrance. Check with the driver.
Admission to the tunnels is 80,000 VND as at May 2011, which includes a guide who may or may not speak English well. While friendly, these guides may attempt to rush the tour or distance you from paid guides/groups -- just indicate that you aren't ready to move on yet and take your time if you feel you're being rushed. Mr. Van Minh provides transport in a modern air-conditioned sedan, and while he speaks little English (your hotel would be able to make arrangements), he drives carefully, rarely uses the horn, and is keen to point out interesting sites along the way. He can be contacted on 09 0856 2927.
There are actually two locations frequented by tourists:
A well defined walking track loops around the area, with things to see spaced at regular intervals, including examples of how people lived and what they ate. There is a 30m section of tunnel which visitors can crawl through (not recommended for the claustrophobic), examples of traps used during the war, and the remnants of bomb craters.
There are numerous souvenir shops at the end of the walking track. Given the location there is some focus on war memorabilia, as well as the traditional Vietnamese souvenirs found elsewhere.
There are a number of stalls selling food and drinks near the entrance. Mid-way around the walking track is a kiosk/restaurant selling drinks and food and ice-cream at reasonable prices, and at the end there are samples of traditional "potato" to try.