Is it appropriate to go to Qingdao to see the sea in April?

It's not appropriate. It is often windy in Qingdao in March and April, and the wind is relatively strong. At present, the highest temperature is about 10 degrees, and the lowest temperature is about 5 degrees. You can estimate that the highest temperature in April is around 15 degrees. If the weather is fine, the seaside will be warm. Without the sun, it will be very cold, and the water is also cold, so it is impossible to play with water. It's best to be in May, neither too cold nor too hot.

I hope I can help you.