Learn Hardcore Korean: yeoreumeneun badasga-eseo suyeonghagi johayo. - In summer, it’s nice to swim at the beach.

에 marks a time (“in summer”), but 에는 = 에 + topic particle 는. By making 여름 the topic, the speaker contrasts or emphasizes “as for summer…” It highlights that what follows applies especially to summer.

What’s the difference between 바닷가에 and 바닷가에서?

에서 indicates the place where an action happens, so 바닷가에서 means “at the beach” (doing something there). 바닷가에 would mark a static location or direction (“to/at the beach” without implying action).

What does 수영하기 mean, and why isn’t it just 수영하다?

수영하기 is the verb stem 수영하- + nominalizer -기, turning “to swim” into the noun “swimming” or “the act of swimming.” In Korean, to say “it’s good to do X,” you use 동사 + -기 + 좋다.

How does the 동사 + -기 + 좋다 structure work?

This pattern literally means “the [verb-ing] is good.” It expresses that something is good or suitable for doing that action.
Examples:
• 읽기 좋다 = “good for reading”
• 보기 좋다 = “nice to look at”
Here, 수영하기 좋다 = “good to swim.”

Why is there no subject like “it” or “people” in this sentence?

Korean often omits subjects when they’re obvious or general. This is a general statement—“It’s nice to swim at the beach in summer”—so you don’t need an explicit subject.

Can I change the tense in 수영하기 좋다?

Yes.
• Past: 수영하기 좋았어요 (“it was good to swim”)
• Future: 수영하기 좋을 거예요 (“it will be good to swim”)

Is the word order flexible in this sentence?

Korean allows some rearrangement, but the predicate (좋다) almost always comes last. Time (여름에는) and place (바닷가에서) typically precede the verb, and the nominalized verb (수영하기) directly precedes 좋다 for clarity.