Is it permissible to photograph nature like mountains, sea, etc.? I read it's forbidden to photograph humans.
As far as I know, it's fine to photograph objects without souls; see IslamWeb:
It is permissible to take pictures of things that have no soul, like trees, rivers, and mountains, and of religious celebrations that have no music, or religious conferences, or news that is beneficial for the Muslims, taking into account religious requirements. May Allah enable you to do whatever He likes and is pleased with.
Narrated Sa'id bin Abu Al-Hasan: While I was with Ibn 'Abbas a man came and said, "O father of 'Abbas! My sustenance is from my manual profession and I make these pictures." Ibn 'Abbas said, "I will tell you only what I heard from Allah's Messenger (ﷺ) . I heard him saying, 'Whoever makes a picture will be punished by Allah till he puts life in it, and he will never be able to put life in it.' " Hearing this, that man heaved a sigh and his face turned pale. Ibn 'Abbas said to him, "What a pity! If you insist on making pictures I advise you to make pictures of trees and any other unanimated objects." -- Sahih al-Bukhari 2225 (sunnah.com); and Sahih Muslim 2109 c, 2110 a (sunnah.com)
Islamic scholars disagree on Photography. The interpretation of these Hadiths varies from a stricter interpretation to a more lenient interpretation.
The making of pictures back in Prophet Muhammad's time meant things like sculpturing of statues and drawing: i.e. Making something out of nothing. The word for picture (verb or noun) meant "to shape" and "to make you into an image".
The consensus behind that being Haram is that Islam does not want images & statues to worshipped & reveared instead of simply following the good examples of the pious.
Photography (and also Videography) today is not a creation of something new. It is a capture of light. It is equivalent to looking at a mirror or water and seeing your reflection except that you're capturing that reflection when it comes to photography. A photographic film is like a mirror that gets exposed to light and captures it, and so it the modern digital camera sensors.
When it comes to "drawing" & "sculpting" there is also a disagreement in the sense that such images are altogether Haram, or whether it is okay as long as images are demeaned. Aishah, the wife of Prophet Muhammad had an image of a Pegasus (Winged Horse) hung as a curtain, and prophet Muhammad asked that it would be taken down. Aisha then made it into cushions or armrests.
Allah's Apostle (ﷺ) visited me when I had screened (my door) with a carpet having pictures on it. He removed it and we made cushions out of that.
There is, however, an agreement among Muslim scholars today that photography of Humans is fine if it was for something beneficial and/or necessary. Examples of that include driver's licenses, passports, and educational lectures.