洞穴

他们在洞穴里探险

tāmen zài dòngxué lǐ tànxiǎn

They are exploring a cave.

洞穴里很潮湿

dòngxué lǐ hěn cháoshī

It's very humid in the cave.

这里有很多天然洞穴

zhèlǐ yǒu hěn duō tiānrán dòngxué

There are many natural caves here.