Xiamen is a beautiful coastal city in China that offers a perfect blend of natural beauty, cultural heritage, and modern amenities. Here's an ideal itinerary for 3 days in Xiamen:

Day 1:

• Start your day with a visit to Gulangyu Island, a UNESCO World Heritage Site known for its colonial architecture, beautiful beaches, and scenic views. Take a ferry from Xiamen Island to reach the island.
• Spend the morning exploring the island's attractions, such as the Sunlight Rock, Shuzhuang Garden, and Piano Museum.
• For lunch, head to the nearby Zhongshan Road Pedestrian Street, a bustling shopping and dining area with a wide range of local and international cuisine options.
• In the afternoon, visit the Xiamen University, one of the most beautiful universities in China, with a picturesque campus and stunning architecture.
• End your day with a stroll along the famous Xiamen seaside promenade, enjoying the sea breeze and the beautiful sunset views.

Day 2:

• Start your day with a visit to the Nanputuo Temple, a famous Buddhist temple with a history of over 1,000 years. The temple is located on the foothills of Wulao Peak, offering beautiful views of the city and the sea.
• For lunch, head to the nearby Hulishan Fortress, a historic military fortification with a museum and a beautiful park. The fortress also offers stunning views of the sea and the surrounding area.
• In the afternoon, visit the Xiamen Botanical Garden, a beautiful park with a wide range of flora and fauna, including rare and endangered species.
• End your day with a visit to the famous Zhongshan Road Night Market, a bustling street market with a wide range of local snacks, souvenirs, and entertainment options.

Day 3:

• Start your day with a visit to the Jimei School Village, a historic village with a unique blend of Chinese and Western architecture, founded by the famous Chinese educator Tan Kah Kee.
• For lunch, head to the nearby Jimei Food Street, a popular dining area with a wide range of local and international cuisine options.
• In the afternoon, visit the Xiamen Science and Technology Museum, a modern museum with interactive exhibits and displays on science, technology, and innovation.
• End your day with a visit to the famous Xiamen International Cruise Terminal, a modern port with stunning views of the sea and the surrounding area. You can also take a cruise to explore the nearby islands and attractions.

I hope this itinerary helps you plan your trip to Xiamen and enjoy all the amazing things this city has to offer!