Entry. Bonaire is part of the Caribbean Netherlands. Passport, visa, onward-ticket, and visitor-tax requirements depend on nationality and can change, so use the official Bonaire entry pages before departure rather than relying on an old guide. Keep proof of your return or onward journey accessible.
Money. The US dollar is the official currency. Cards are widely accepted in Kralendijk, but cash remains useful for small stops and places outside town. ATMs are concentrated around the capital. Prices are high because much of what the island uses must be imported.
Language. Papiamentu is the language you will hear most often, with Dutch used in government and education. English and Spanish are widely understood in tourism. A greeting before launching into a request is appreciated; bon dia, bon tardi, and danki go a long way.
Nature fee. Users of Bonaire's protected water and visitors to Washington-Slagbaai must follow STINAPA's current nature-fee rules. Buy through the official channel, keep the confirmation available, and ignore resellers that make the process look like an excursion.
Safety. Bonaire is generally straightforward, but isolated dive sites invite petty theft. Leave nothing visible in a parked vehicle and avoid taking valuables to the beach. The stronger risks are environmental: sun, dehydration, rough shore entries, traffic on dark roads, and misjudging your diving ability. Tap water is drinkable; carry it generously.