If you are visiting Malaysia and you are a nature or water or natural scenery lover, I would say you must visit Langkawi.
Ferry I won’t suggest to family or people who are not interested to spend much time on traveling as you need to travel around 7 hours in bus (450-500 KMS) to reach the ferry service. And traveling in ferry might give you nausea feeling as it’s shaking. So better book flight in advance which you can get at rate of 1400-2000 INR onwards (15$+).
Or else visiting Penang and taking ferry is a worth option for explorers.
MD Note The Point
📌In order to travel to Langkawi you need to book the same flight which you booked from your country to Malaysia.
Example: if you are traveling from India in Airasia, book the same to Langkawi too to avoid changing airport.
Catch the same airport.