Sea kayaking is the best way to explore the smaller water channels, sea caves, and hidden lagoons (ho) that are inaccessible to larger boats. Most overnight cruise itineraries include two to three hours of guided kayaking; standalone kayak tours can also be booked through operators in Bai Chay for day trips into the bay.
The most famous kayaking destination is the interior lagoon at Luon Cave — paddling through a low arch into the enclosed water beyond, with limestone walls on all sides and monkeys visible in the vegetation above. The experience is genuinely extraordinary and not well reproduced by photographs. The water is usually calm enough for complete beginners. Sit-on-top kayaks are the norm; no prior experience necessary.