1. Dau Go Cave, also known as Hang Dau Go, is one of the most popular and impressive caves located in Halong Bay, Vietnam. The cave is located on Dau Go Island and is about 6 kilometers from the mainland. It is known for its stunning limestone formations, stalactites, and stalagmites.

The name \"Dau Go\" translates to \"Wooden Head\" in Vietnamese, and the cave gets its name from a legend associated with it. According to folklore, it is said that the cave was once a hiding spot for the Vietnamese during the Mongol invasions. The story goes that the local people used wooden stakes to ambush and defeat the Mongol fleet, hence the name \"Wooden Head.\"

The cave consists of three main chambers, with the first chamber being the largest and most impressive. The chamber is adorned with numerous stalactites and stalagmites in various shapes and sizes, creating a breathtaking spectacle. The second and third chambers are smaller but still feature interesting limestone formations.

2. The working time of Dau Go Cave is from 8:00 AM to 6:00 PM. It is recommended to check with local tour operators or the Halong Bay Management Board for the most up-to-date information. Unfortunately, no phone number specifically for the cave is available.

3. To visit Dau Go Cave, you would typically need to book a tour or hire a boat to take you around Halong Bay. There are several options available, ranging from day tours to overnight cruises. The ticket price for visiting Dau Go Cave is usually included in the overall tour package.

The cost of the tour can vary depending on the duration and inclusions, such as meals and accommodation. It is advisable to compare prices and services from different tour operators before making a decision. Transportation to and from Halong Bay is typically arranged by the tour operator, with options that include bus transfers from Hanoi or private transportation.