If Hong Kong is the gateway to China, then Shenzhen is the necessary front porch. Just 30 years ago, Shenzhen was a small town by the sea. Now it's one of China's biggest and most important cities.
The theme parks are not world class like Hong Kong's. Not really worth a special trip, they might be a fun option if you have kids, clustered just north of Shenzhen Bay around the Window of the World stop on Line 1 of the metro.
Ping An IFC: It is the world's 4th tallest building and China's second tallest, with a world-class observation deck at 550 meters (1,804 feet), and the world's second highest luxury hotel.
KK100: About 4 km away, the 442-meter (1,450-foot) KK100 is the second tallest in Shenzhen and among the world's top 20 as of 2016. It's observation deck gives a good view of the sea.
Also read: China's 10 Tallest Skyscrapers — About Half of the World's Top 20
Shenzhen's city parks are places to exercise and to see the local people and scenery. See more on these on Free Things to Do in Shenzhen.
Shenzhen has mountains, hills, and beaches. They are also good places for exercise and a scenic break from the big city. For example, Wutong Mountain (梧桐山Wútóng Shān; #11 of Things to Do on TripAdvisor) is the second tallest mountain in the Pearl River Delta after Hong Kong's Tai Mo Shan. You may also be interested in Shenzhen Camping Places.
Shenzhen is a shopping opportunity next to Hong Kong. Beware about the quality, tricks and lack of reliable warranties. The better buys include Chinese produced clothing, jewelry, electrical appliances, and digital products. More on Shenzhen Shopping>>>
Luxury bargains? Foreign brands, high fashion, and luxury products actually cost more in Shenzhen than in Hong Kong! Wealthy Mainland shoppers prefer to shop in Hong Kong. See What Mainland Expats Want to Buy in Hong Kong in 2016 for the relative advantages of both cities.
Shenzhen is nowhere near being a gastronomical capital like Hong Kong, but you'll find cuisines from all over China due to the migration of large numbers of people from all across the country. There are also many Asian restaurants and Western-style restaurants. They are notably less expensive than those in Hong Kong. More about Shenzhen restaurants/food>>>
Like Hong Kong, Shenzhen's weather is fairly mild with plenty of rain and sunshine. The air quality is considered among the best of China's big cities. However, smog is an increasing problem due to more cars per capita than almost all other cities and Guangdong's factories. See more on Shenzhen Weather.
Typhoons are rare. Shenzhen is affected by a typhoon once in two years on average. For more information, see Hong Kong Typhoon Season.
Most people go to Shenzhen through the Hong Kong border. But there are other ways... See more on Shenzhen Transport.
Guangzhou is now 72-hour-visa-free for transit via Baiyun Airport. This visa free travel permits you to travel around all of Guangdong Province including Shenzhen!
We can help you explore Shenzhen and discover more about the area, and much more: