To use WhatsApp on a cruise ship in 2026, you typically need to purchase an onboard Wi-Fi package, as standard cellular data at sea is prohibitively expensive due to maritime roaming rates. Most modern cruise lines, such as Royal Caribbean and Carnival, offer tiered internet plans; a "Social" or "Basic" plan is usually sufficient for WhatsApp text messaging, though you may need a "Premium" or "Stream" plan for voice and video calls. A notable exception is Disney Cruise Line, which famously allows guests to send and receive WhatsApp text messages for free without a paid package (though media like photos and videos are excluded). For other lines, the "pro" strategy is to put your phone in Airplane Mode first, then toggle on Wi-Fi to connect to the ship's network. This prevents accidental "cellular at sea" charges. If the ship's Wi-Fi is too slow, you can wait until you reach a port of call to use local roaming or an eSIM, which is often significantly faster and cheaper than the satellite-based internet found on board.