When planning a trip to Sri Lanka, it's crucial to ensure that your passport remains valid for at least six months beyond your return date. Children, irrespective of age, must also have their own passport or identity card. Additionally, obtaining a visa is necessary for your stay, which can be conveniently done online at http://www.eta.gov.lk/slvisa. The cost of a visa for a 30-day, double-entry stay is around $50 USD, while children under 12 receive theirs free of charge. After filling out your details on the visa application link and making the necessary payment, you'll promptly receive confirmation of your application. Note that this confirmation doesn't serve as your visa; you'll receive that later. If you don't receive the email confirmation, check your spam folder or contact the sender. Upon arrival in Sri Lanka, you'll be required to fill out an 'arrival' card, available at the immigration desk. For stays exceeding 30 days, it's advisable to contact the Sri Lankan Embassy to apply for an extended visa. Ensure you have all necessary travel documents in order, and if you're not a Dutch national or resident, it's essential to consult the relevant embassy or consulate for specific travel requirements.