A boat trip adds two risks a beach day mostly doesn't have to deal with — motion, and much less shade — on top of the sun exposure any day at the coast already carries. None of this needs specialist gear, and all of it is standard NHS advice rather than anything boat- or Spain-specific, which makes it easy to prepare for regardless of which trip or operator is involved.
Motion sickness
The NHS's core advice for motion sickness on a boat is about where you sit and what you look at more than anything you need to buy. Sitting in the middle of a boat, where movement is felt least, and looking straight ahead at a fixed point such as the horizon, are the first two recommendations. Closing your eyes and breathing slowly, or getting fresh air where possible, both help; reading, watching a phone or film screen, and tracking moving objects like the waves themselves all make it worse. On the food side, the NHS suggests avoiding a heavy meal, spicy or greasy food, and alcohol before travelling, and specifically mentions ginger — as a tablet, biscuit or tea — as worth trying. For longer trips, a pharmacist can recommend over-the-counter options including tablets and, for anyone over 10, motion-sickness patches or acupressure bands.
Sun protection
The NHS recommends at least SPF30 sunscreen with good UVA protection (look for a high star rating on UK products), applied generously around 30 minutes before going out — roughly 6 to 8 teaspoons, about 35ml, to cover an adult's entire body. It needs reapplying every two hours, and immediately after swimming, sweating or towelling off, even if the product claims to be water-resistant. A boat deck typically offers less shade than a beach, and water reflects additional UV onto skin that's already exposed, so the standard "seek shade 11am–3pm" advice is harder to follow at sea — sunscreen, a hat and covering up matter more, not less, on a boat than on the sand.
Heat exhaustion — what to watch for
Heat exhaustion is the more common, less severe condition a hot day on open water without much shade can bring on: the NHS lists tiredness, dizziness, headache, nausea, heavy sweating with pale, clammy skin, cramps, a high temperature and unusual thirst as its main signs. The first-aid response is straightforward — move to a cool spot, remove unnecessary clothing, give water or a rehydration drink, and cool the skin with a cool, damp cloth or fanning — and someone should start to feel better within 30 minutes. If they don't, or if symptoms tip into heatstroke instead — a very high temperature, hot skin that's stopped sweating, a fast heartbeat, confusion, or loss of consciousness — the NHS is explicit that this is a medical emergency requiring immediate help, not something to keep monitoring and hope improves.
A simple checklist
Sunscreen (SPF30+, reapplied every two hours), a hat and cover-up for exposed skin, water to stay hydrated through the day, a light pre-trip meal rather than a heavy one, and — for anyone prone to seasickness — a seat toward the middle of the boat and a fixed point on the horizon to look at. None of it requires planning much in advance, but all of it is easier to arrange before boarding than partway through the day.
See this site's archived boat party pages for what a Marbella boat trip originally covered, and the Marbella & Puerto Banús guide for the wider destination.
Questions people ask
Where's the best place to sit on a boat if I get seasick?
The NHS recommends sitting where movement is felt least — the middle of a boat rather than the front or back — and looking straight ahead at a fixed point such as the horizon rather than at moving waves or a phone screen.
How much sunscreen should I actually be using?
The NHS advises around 6 to 8 teaspoons (roughly 35ml) to cover an adult's whole body, applied generously 30 minutes before going out, with at least SPF30 and reapplication every two hours — sooner after swimming, sweating or towelling off.