The amusement park was extremely crowded on the weekend.
The train at this hour is always packed.
Alternate spelling of the same word; 激混み is more common.
Most common spelling; 混み is the standard kanji for 'crowded' in this compound.
Alternate spelling using 込, which is also used in 混雑 and related words.
Compound of 激 (げき, 'intense') and 混み (こみ, noun form of 混む 'to be crowded'). A relatively modern colloquial formation.