
Siem Reap
Located in northwest Cambodia, Siem Reap is a resort town and the portal to the Angkor ruins. The ancient complex was the base of the Khmer kingdom during the 9th through 15 centuries. Angkor's large complex of stone buildings features the main temple of Angor Wat, which also is featured on the Cambodian flag. You can also see mysterious expressions displayed at the Bayon Temple at Angkor Thom. The Old Market in Siem Reap is popular because of its bar, pubs, and restaurants.
Best Time To Visit
Visit the attraction between November and April when skies are clear and sunny.
You Should Know
Night markets in the Old Market area set up in the afternoon and stay open until late at night. Before you visit the temple complex of Angkor Wat, pay a visit to the Angkor Wat Museum. The museum allows you to learn more about Angkorian antiquities, and the ancient history and culture of the area during the Khmer era. 
Angor Wat
You simply cannot take one of the Cambodian river cruises featured online without visiting Angor Wat. You will need to head deep into the rainforest to find the lost city and religious monument. The temple facility is distinguished as being the biggest in the world. Large tree roots wrap around many of the temples and bas-relief carvings tell ancient tales.
Best Time To Visit
November through April is the most auspicious time to see Angkor Wat.
You Should Know
The temple has been shared by two religions – Hinduism and Buddhism. At the end of the 12th century, the temple was being used for Buddhist worship. It is still used for practicing Buddhism today. The Angor Wat temple was thought to be designed for funerals because of its westward-facing direction. Usually, Angkorian temples face east while death is symbolized by facing a building west. The building of Angkor Wat required 300,000 laborers and 6,000 elephants working over a 35-year period.
Kampong Cham
Kampong Cham is Cambodia's third-largest city. The rural-like geographical setting of the city contrasts with its thriving city center. While most of Cambodia is primarily Buddhist and Khmer, a large portion of Kampong Cham is Muslim and Christian as well as Chinese. As a result, the city features various religious centers and a variety of foods.
Best Time To Visit
It is best to see Kampong Cham from November through April.
You Should Know
The local market is authentic and does not feature any touristy gimmicks. It is simply a place where the residents buy spices, meat, products, clothes, and toys. Koh Paen Island allows you to experience the farm life in Kampong Chang. You can rent a bicycle and do some exploring. Mountain Srey and Mountain Pros represent two mountains situated west of the city. Mountain Pros is home to pagoda temples, fruit statues, and vendors selling sugar cane juice. If you visit Mountain Srey, you will need to take 308 steps to get to the top. A magnificent abandoned temple will greet you at the top.
Kratié Town
If you want to see Mekong dolphins, you can spot pods when you visit Kratié Town. This part of Cambodia allows you to experience Cambodian village life while seeing some one-of-a-kind sites. The town is home to several pagodas and the largest wat in Cambodia.
Best Time To Visit
Try to visit Kratié Town in November or December when it is drier and more temperate.
You Should Know
Koh Trong Island is a good place to cycle. You will need to catch a ferry, which will deliver you to the island or sandbar in about 5 minutes. It is only about 9 miles around the island, which gives you plenty of time to enjoy the scenery, including the rice paddies, pagodas, and floating village. In the center of town sits Krong Krachen Pagoda, whose gold and pink façade glimmer at sunset.
Tonle Sap Lake
During the wet season, Tonle Sap Lake is the largest freshwater lake in Cambodia and Southeast Asia. After the rains, the lake shrinks but is still considered a large body of water. Stretching from Phnom Penh to Angkor Wat, the lake is known for providing for the agricultural needs of the surrounding communities as well as the country's fishing industry.
Best Time To Visit Visit Tonle Sap Lake during the dry season, or November to April, when things are calmer and there are mostly sunny skies. Birds visit the area from December to May, so you may want to schedule a time to see the lake in December.
You Should Know
One of the most attractive floating fishing villages on Tonle Sap Lake is Prek Toal. The village features restaurants, a school, a hospital, and a pagoda. Tonle Sap features fishing lots and floating houses where locals raise and catch fish for a living. 
Han Chey Mountain
Known officially as Chey Kiri Mountain, Han Chey Mountain sits on the north side of the Mekong River. You can climb the mountain by taking 295 stair steps. The mountain is home to many temples and a pagoda.
Best Time To Visit
Add Han Chey Mountain to your travel itinerary from November to April.
You Should Know
A temple, called Pra Sat Neang Khmao, lies in the valley of the mountain and is made of stones, each is seven square meters. The pagoda at the mountain's top is called Wat Han Chey. From here, you can enjoy gorgeous views of the Mekong River. A vihara or Buddhist monastery sits at the site.
Phnom Penh
The busy capital of Phnom Penh lies at the confluence of the Tonle Sap and Mekong rivers. It was once a base for the Khmer Empire, and later a hub for French colonials. The city's riverfront promenade features bars, restaurants, and parks. Top sites include the National Museum, the Royal Palace, and Silver Pagoda.
Best Time To Visit
Phnom Penh is always pleasant to visit in the spring or fall, especially April or November.
You Should Know
The city's Central Market boasts an Art Deco décor. Besides the Khmer New Year in mid-April, the holiday, P'chum Ben is another significant celebration. During the festival, locals visit pagodas to make offerings to deceased relatives. During the rainy monsoon season in September and October, Phnom Penh can receive a whopping 200 inches of precipitation in one month. 
Hoh Chi Minh City, Vietnam
Hoh Chi Minh City is a thriving metropolis and is a great way to conclude or begin a Cambodia river cruise. As the largest city in Vietnam, it offers river cruise-goers with contrasting sites to see – places that may be modern or traditional. When you visit the city, you can enjoy shopping and dining in upmarket venues as well as check out the vendor markets at night.
You Should Know
The city boasts the second-largest number of motorcycle owners in the world, only falling second after Taiwan. Therefore, be very careful about crossing the street. Ho Chi Minh City has some of the best street food in Vietnam. Try vendor specialties, such as cao lau, which is a pork noodle dish, or pho, rice noodles and broth.
If you have never been to Cambodia before, you want to book a river cruise when the weather is more stable and the temperatures are tolerable. Cambodia has warm weather all year long, accompanied by a dry season and a rainy season. Keep in mind that the temperature will continue to climb, beginning in April. When temperatures peak, they can hit over 100 degrees Fahrenheit. However, you can enjoy air-conditioning on board your ship, which makes things more tolerable.
Cold Weather - November to February - Best Season
Although it is considered the cooler season, temperatures don't drop below 70 °F. Making this time of the year the perfect time to explore the unique sights of Cambodia. Schedule a trip to Hoh Chi Minh City in November or December to enjoy drier weather.
Warm Weather - March- June - Good Season
During these months the temperatures in temperatures peak, they can hit over 100 degrees Fahrenheit. Keep in mind that the temperature will continue to climb, beginning in April. However, you can enjoy air-conditioning on board your ship, which makes things more tolerable.
Rainy Season - June - September - Low Season
If you wish to avoid problems with flooding, you do not want to go during September or October when the rains set in. The heavy rains during this time tend to be accompanied by strong winds.