The short answer
Pack for heat, salt and sand, and pack less than you think. Cartagena sits at sea level in the Caribbean and it is warm and humid all year. Linen, cotton, a swimsuit you're happy to spend eight hours in, flat shoes, sun cream, a hat and a refillable water bottle will cover most of a week. If you're coming out to us on Tierra Bomba, the only extra rule is that the day's things go in one soft bag rather than a rigid case.
We live 25 minutes offshore, so we watch several hundred people a month step off a boat with the wrong bag and the right intentions. Here's what we'd tell a friend.
The city list
Cartagena's old streets are cobbled and uneven, so flat shoes win. Sandals in the day, something closed if you're walking a lot. Evenings inside the walls are dressier than the beach but nobody needs a jacket: it does not get cold.
Sun cream matters more here than the forecast suggests, because the cloud cover burns off fast and the reflection off the water does the rest. Bring more than one bottle or buy it in the city, where it costs less than on any island.
A hat with a brim, sunglasses, and a light long-sleeved shirt are worth more than any amount of after-sun. We wear the shirt in the boat.
A refillable bottle. Also a small dry bag or a zip-lock for a phone and a passport, which is the single most useful thing anyone brings out here.
The day bag for the boat
One soft bag, packed so you can hold it in one hand. Our boat leaves the Muelle de la Bodeguita at 10am, 11:30am and 5pm, and the crossing takes about 25 minutes. The water is usually smooth and much calmer than the run out to the Rosario Islands, though in windy weather it gets choppy. Getting on and off requires some agility either way, and a hard-shell suitcase makes that harder for you and for whoever is handing it across.
If the tide is very high or the sea is rough, we dock in Bocachica village instead, about a mile from us, and you ride pillion on a motorbike taxi from there. That is a genuinely good five minutes of your holiday, and it's also the moment you'll be glad your bag has a strap.
In the bag: swimsuit, sun cream, hat, a book, phone in something waterproof. That's it.
What you don't need to bring
Towels: your room rate and your day pass include towel service, so leave the beach towel at home.
A sun lounger scramble: if you're staying with us your favourite lounger is reserved for you every day, and you pick it when you check in. Day visitors choose a lounger when they book, from $5 to $30 depending on whether you want poolside near the music or the quieter beach row.
Your own food and drink: we don't allow it. We aren't going to lose our minds over a banana in your bag, but lunch from elsewhere is a no, and bringing your own alcohol only works for full privatisations, with corkage.
Snorkel gear: our beachfront leads out to open ocean and our house reef sits at 6 metres, which is too deep to snorkel comfortably. If you want to see it, book an hour of scuba with us instead. No experience needed.
Things people forget
Cash in small notes. Not everywhere in Cartagena or in Bocachica village takes a card.
A plug adapter if you're coming from Europe. Colombia runs on the same flat two-pin plugs as the US.
Medication in your hand luggage. We're on an island with no pharmacy, and the last boat back to the city leaves us at 5:30pm.
And tell someone at home you'll be offline. There's no phone signal on the island. If you need to reach us before you arrive, WhatsApp is the way, and we answer reservations enquiries between 9am and 9pm.
Shoes, specifically
The walk from our gate to the water is about 200 metres of sandy track, and the sand here is volcanic, so it's dark and it holds heat. Bare feet are fine early and late. In the middle of the day you'll want something on them. Flip flops that survive salt water are perfect; anything suede is not.
It's also worth saying plainly that we're not built for wheelchairs. A boat ride and a sandy track is the honest description of getting here, and we'd rather you knew before you packed than after.
Season by season, briefly
There is no cold season. What changes is rain: September and October are the wettest months, when a heavy shower can arrive in the afternoon and be gone within the hour. Pack a light rain layer for those two months and nothing heavier. From December to April it's drier and windier, which is lovely on a sun lounger and choppier on the boat.
If you're deciding when to come at all, we've written about the rainy season honestly elsewhere on the site rather than pretending it doesn't happen.
One last thing
Whatever you forget, most of it is buyable in Cartagena on the way. Sun cream, a hat, a swimsuit, flip flops: all of it is within a few blocks of the dock. What you cannot buy at the dock is time, so leave with a margin, because the boat goes when it goes.
See you on the boat.