The concept of "starry sea" is usually used to describe the vast starry sky and the

 boundless sea. If you are referring to the inability to see the bright starry sky at 

night, this is mainly caused by the following reasons:

Light pollution: This is the biggest reason why you can’t see the stars. In cities 

and other densely populated areas, a large amount of artificial light sources 

(such as street lights, billboards, car lights and building lighting) generate a

 large amount of light pollution. These intense rays of light scatter across the sky, 

increasing the background brightness of the night sky and causing stars to become

 less visible or even visually disappear completely.

Air pollution: Dust, smoke, and other pollutants in the air can absorb or scatter 

light from stars, reducing their visibility. On days with haze or poor air quality,

 the stars may be completely obscured.

Climate Change and Weather Conditions: Clouds, fog, and other weather 

conditions can also block starlight. In addition, as climate change progresses, 

changes in weather patterns in some areas may lead to an increase in cloud 

cover and reduce the frequency of clear night skies.

Geographic location: Stargazing conditions are often poor in cities or other

 areas with heavy light pollution. In contrast, remote rural areas or inaccessible 

places such as oceans and mountains are more suitable for stargazing.

In order to better appreciate the starry sky, you can choose to go to an area 

with less light pollution on a night with no moonlight, fresh air, and no clouds.

 In addition, some countries and regions have established "dark sky parks" or "

starry sky reserves" specifically to protect the night sky from light pollution and 

provide an ideal stargazing environment.