Learn Hardcore Japanese: watasi ha ryokou ga suki desu.

は is the topic marker in Japanese. By saying 私は, you establish “me” as the topic of your sentence (“as for me…”). It’s different from a subject marker (like が). Topics can sometimes be omitted if they’re understood from context, but here 私は makes it explicit you’re talking about yourself.

Why is 旅行 marked with が instead of を?

Because 好き is a na-adjective, not a transitive verb. With 好き, the thing you like is marked by が:
• 旅行が好きです。 – “(I) like travel.”
If it were a verb like 読む (“to read”), you’d use を: 本を読む.

What part of speech is 好き and how does it work grammatically?

好き is a na-adjective (sometimes called a “nominal adjective”).
• As a predicate: 好きです (“is liked”)
• Before a noun it takes な: 好きな映画 (“a movie [that I] like”)
It never conjugates like an -い adjective; instead you attach だ／です or its negatives.

Why is there no verb after 好き?

Because 好き itself functions as an adjective-predicate. To make it polite, you add the copula です. In plain speech you could say 旅行が好きだ. There’s no need for a separate “to be” verb beyond だ／です.

Can you omit 私は and just say 旅行が好きです?

Yes. Japanese often drops the topic when it’s clear from context. 旅行が好きです naturally means “I like travel” if you’re talking about yourself. If you need to clarify “you” or “they,” you’d add あなたは or 彼は, etc.

How would I say “I like to travel” using the verb 旅行する?

Convert 旅行する into a noun phrase by adding の, then mark it with が:
• 旅行するのが好きです。 (“I like traveling.”)
You could also shorten it to 旅行するのが好き in casual contexts.

How do I express “I don’t like traveling”?

Use the negative form of the copula or 好き structure:
• Casual: 旅行が好きじゃない。
• Polite: 旅行が好きじゃないです。 or 旅行が好きではありません。

How would I ask someone, “Do you like traveling?”

Flip it into a question by adding か at the end:
• 旅行が好きですか。
You can also use rising intonation in speech: 旅行が好きです？