If you want to be connected without having to depend on your hotel, or a restaurant or any other public place connected to wifi, I would advise you to buy a local SIM card on your arrival.
Depending on the country you travel to you might be disappointed to discover that very few places have wifi. You may also need to make a local call because you cannot find an address. Besides, it is cheaper than activating roaming with your usual sim card. Even if you have a local number, when you install the SIM on your mobile to use the data, you can continue using your whatsapp as usual. In airports, the large telephone companies are usually present. Be sure to tell them you want a local SIM.
Be aware that in some countries they sell cards for tourists that last for a stipulated time. However, these can be more expensive and have poor coverage.