You should go in Bangkok and then you could take transport to Krabi

Krabi is a popular tourist destination in Thailand known for its stunning beaches and limestone cliffs. To get to Krabi, you typically have several options:

By Air:
Krabi International Airport (KBV): The most convenient way to reach Krabi is by flying directly to Krabi International Airport. Many airlines operate flights to Krabi from major cities in Thailand and other countries.
By Land and Sea:
Bus: You can take a bus to Krabi from various cities in Thailand. Buses are available from Bangkok, Phuket, and other neighboring provinces.

Train: While there is no train station in Krabi itself, you can take a train to Surat Thani or Trang and then continue your journey to Krabi by bus or van.

Car: If you prefer driving, you can rent a car and travel to Krabi. The journey may take several hours depending on your starting point.

By Sea:
Ferry from Phuket: If you're on the nearby island of Phuket, you can take a ferry to Krabi. The ferry ride offers scenic views of the Andaman Sea.

Long-tail Boat: Once in Krabi, you can use local long-tail boats to visit nearby islands and beaches.