A low stone gateway to an enclosed lake
The bay’s management board describes Luồn Cave in the Bồ Hòn area as a flooded passage linking the open bay to an enclosed lake. Visitors can enter by sampan or kayak under the arrangements permitted at the site. The tide changes the clearance; at times passengers need to duck. The rhythm comes from the water itself, not a staged effect.
Observe without disturbing
The inner lake is a natural habitat; the site’s management information notes the presence of rhesus macaques in the area. Do not call to, feed, or approach wildlife. Confirm whether kayaking is available, water conditions, and that day’s safety requirements before setting out; operating arrangements can change.