There are 4 giant Jovian planets in the solar system: Jupiter, Saturn, Uranus and Neptune. Place Pluto, Eris and 2007 OR10 apart as they are very small and look like the moon; their surface is frozen and do not consist of gas. We will speak again.
These 4 giant planets do not have a solid surface. If you dive with a spaceship in the atmosphere of Jupiter or Saturn for example you will sink without ever meeting the ground. Finally you will not be able to move forward because the atmosphere will have become very dense; first it will look like fog and then very dense rain that will turn into a liquid and gelatinous mixture to become gradually solid near the center.
At the same time that you plunge into this atmosphere, the temperature will increase to finally reach more than 10000 ° C just like the pressure which will increase until unbearable values that would crush even the machine the most resistance until giving it the thickness of ‘a sheet of paper !
In the meantime, during your descent, you will probably see many lightning and thunderstorms, and you will probably be swept away by storms and cyclones blowing more violently than on Earth, sometimes at 2000 km / h ! These are very inhospitable worlds in which it is impossible to live and it is better to observe from a distance, for example through a telescope.