Translation guide
The line where the earth and sky meet, or a metaphorical limit of knowledge or experience.
The visible line where the earth or sea meets the sky.
The limit of a person's knowledge, experience, or interest.
To expand one's experiences or knowledge.
地平線 is used for the horizon over land, while 水平線 is specifically for the horizon over the sea or large bodies of water. Using the wrong one can sound odd.
desert horizon
For 'broaden one's horizons', 視野を広げる is the most natural and common expression. Avoid literal translations like 地平線を広げる.
The ship disappeared over the horizon.
I want to broaden my horizons.
An island is visible beyond the horizon.
The horizon is dyed crimson.
New experiences broaden one's horizons.
Reading broadens your horizons.