The diversity of an East Asian cruise means that almost every day is a new stop, often in a new country, with a chance to learn about a new unique culture and ancient traditions. From the Great Wall in China to the World War II battles of Iwo Jima, a cruise-led history lesson can span thousands of years. Asia’s high season for cruises begins in December and lasts until March, with deals generally available in October, November and April. Not long ago only upscale lines and expedition ships ventured to Asia, but over the last decade the largest cruise lines have been steadily sending bigger ships here, including Princess Cruises and Royal Caribbean International. The smaller vessels dock in the heart of major cities, and go to the most remote areas, while the largest ships offer smoother sailing through what can be rough seas between far-away destinations like Ho Chi Minh City and Singapore. For cruisers looking to learn more about Asian history, there are several sites worth visiting on extended shore excursions, in addition to the obvious ones like the Great Wall and Angkor Wat. Over the last few years, cruise ships have been spending more time in the most popular ports like Beijing and Bangkok, giving passengers the opportunity to take overland tours or long day trips, as well as experience the nightlife. Doing excursions on your own in places like China or Vietnam can be very cheap, especially compared to the ship prices. However, when time is tight and language is a concern, it makes sense to use the cruise tour or another company that guarantees that you will get back to the ship in time. If time is not an issue, here are five port excursions, slightly off the beaten path, that you can do on your own. Ho Chi Minh City’s war tunnels Known to a generation of Americans as “Saigon”, this city is a treasure trove for Vietnam War buffs. There are plenty of sites related to the war within the city limits, but one of the most interesting is about an hour outside town. The Cu Chi Tunnels were built by the Viet Cong during the war to hide from the Americans and the South Vietnamese. The Viet Cong used these hundreds of kilometres of underground passageways to hide their soldiers and transfer food and weapons. The outdoor museum is reached by driving past green fields and water buffalo. You will find the remains of an American tank, several kinds of booby traps that awaited US troops patrolling the area, a video about making the tunnels, and the highlight -- a chance to scurry through sections of the tunnels that seem impossibly small, but were actually widened to accommodate tourists. Many local operators offer an excursion to the tunnels for much less than your ship, but make sure they are certified and will get you back to Ho Chi Minh City in time for departure. Viator, an online booking engine for tours, offers a five-hour excursion with transportation and an English-speaking guide from only $25 per person. Beijing opera Several cruises begin or end in Beijing, and many others overnight there, giving passengers the opportunity to sample the city’s nightlife. An intriguing nocturnal activity for history buffs is Chinese opera, a tradition that dates back, in its modern form, to the 1700s. Performances offer a historical view of China’s past, with many shows based on ancient epics. The bold costumes, dramatic masks and makeup, and acrobatics that often happen while wielding swords, make for a unique and entertaining night out. Two theatres offer daily opera with subtitles in English, both in collaboration with the Beijing Opera Company: the 800-seat Chang\'an Grand Theater and the teahouse-style Liyuan Theater . The tourist-oriented Liyuan Theater is housed in the Qianmen Hotel, and lets audience members watch the performers apply make-up before the show starts, and sip tea during the performance. Beijing’s cruise port is actually in Tianjin, so cruisers either spend the night in a Beijing hotel or get there by train or private car. The bullet train takes 30 minutes. Taxis are plentiful and inexpensive, but few drivers speak English so make sure you have your destination written down in Chinese.