Rosario Islands, how to plan a day that actually delivers

What the Rosarios actually are

A protected archipelago of 27 small islands about 45 minutes southwest of Cartagena. Coral reef, mangroves, water that goes from deep blue to glass green, and a scattering of private homes and beach clubs.

There is no single island you go to. The day is a route: a swim stop, a snorkel spot, a club for lunch, maybe a quiet cove on the way back.

Private boat versus shared

A shared launch is cheap and runs to a fixed timetable with 30 other people. You get where you are going, but you stop when they stop and leave when they leave.

A private boat costs more and changes everything. You choose the route, you swim where the water is best that day, you eat when you are hungry, and you are not queuing for anything. For groups of four or more the per person difference gets small quickly.

• ·Small speedboats suit couples and groups up to six for a fast, flexible day.
• ·Larger motor yachts and catamarans suit eight to twenty with shade, sound and a proper galley.
• ·Crew matters more than the hull. A captain who knows the reef finds clear water on a bad wind day.

The timing that makes it good

The sea is calmest early and the light is best before noon. Wind usually builds through the afternoon, so the return leg is bumpier than the outbound.

Leave the marina at 9am and you get two hours of glassy water before anyone else arrives at the good snorkel spots.

Where to eat

Most beach clubs run a day pass that includes a lounger, lunch and pool access. Quality varies wildly. The good ones limit numbers, serve real seafood and have shade that is not a plastic chair under a tree.

Alternatively eat on board. On a chartered boat a cook can serve lunch at anchor, which is quieter and often better than anything on shore.

What to bring, and what to leave

Pack light, but do not miss these.

• ·Reef safe sunscreen, reapplied twice. The reflection off the water doubles the exposure.
• ·Cash for the national park fee and anything bought on the islands.
• ·A dry bag for phones. Tenders get wet on the transfer to shore.
• ·Leave jewelry and anything you would hate to lose in the safe at the hotel.

How we run it

We book the vessel, the crew, the club or the on board lunch, the transfer from your door to the marina and back, and we watch the wind forecast so the route is set on the morning rather than a week out. Tell us the group size and the date and we will come back with two or three vessel options and the full cost.