The Blown-Out Day: Planning a Dive Week

A blown-out day is planned, not lost. Build one spare day into every four or five dive days, decide before departure what that day is for, and book the land side in advance so the decision is already made when the wind arrives. The dive week then survives a bad forecast without a scramble.

How do you plan a dive week so a blown-out day is useful?

Count dive days, not calendar days. A seven-night trip with five dive days leaves two spare mornings. That is the standard shape for a week in a trade-wind destination, where a day or two of wind is normal rather than exceptional.

Decide the spare day's job before the trip. Three jobs work: a skills day on land, a travel day to somewhere inland, or a rest day with no diving at all. Pick one per spare day and write it into the plan.

Keep the spare day flexible in the last 24 hours. Wind forecasts at 24 hours are useful, at seven days they are not. A diver who books a boat on the spare morning and a land trip on the spare afternoon will lose one of them.

Book the land side early. Lodging, transport and any guided inland day fill up in high season, and the spare day is the one with no reservation behind it. A diver who has already arranged planning a stay in Santa Fe or any other inland base has a fallback that does not depend on the marine forecast.

Keep the dive kit packed and dry. A blown-out day is often followed by a good one. Rinsed and hung gear on the spare day means the next morning starts with a boat or a shore entry, not with a search for a missing fin.

What does altitude and dry air do to a diver on a land day?

Altitude reduces the pressure of the air around the diver, and dry air removes moisture from the airway. Both matter after diving, and both matter more than most divers expect.

Diving leaves residual nitrogen in the tissues. Flying after diving is restricted because the cabin altitude is lower in pressure than sea level. Driving to altitude does the same thing more slowly. DAN, the Divers Alert Network, publishes guidance on altitude exposure after diving and recommends waiting before going to height, with the wait depending on the dive profile and the altitude reached.

A common planning figure is that a diver should not go above 300 metres (about 1,000 feet) for 12 hours after a no-decompression dive, and not above 2,400 metres (about 8,000 feet) for 18 hours. Those figures come from the same family of guidance as flying-after-diving rules, and they are conservative rather than exact. A diver who plans an inland day at 2,000 metres should treat it as a post-dive altitude exposure and schedule it late in the trip, not on the last dive day.

Dry air is the second effect. Compressed gas and dry cabin air both dry the airway, and a diver who has been breathing from a regulator for a week often notices a sore throat and a cough on the first land day. Water, not coffee, is the fix. A diver heading to altitude should drink more than usual for the first 24 hours.

Cold is the third. Altitude means lower temperature, and a diver who has spent a week in 28 degree water may not have packed for 5 degrees at night. A layer and a hat are worth the space.

What should be booked before the season starts on a dive island?

Book the fixed points first: flights, the first and last night of lodging, and any liveaboard or boat space that sells out. On a small island, boat capacity is the binding constraint, not hotel rooms.

Book tanks and weights if the plan is shore diving. A dive shop that rents cylinders for a week will hold them for a reservation and release them for a walk-in. The same applies to a vehicle with a tank rack.

Book the land day. Inland lodging, a rental car for the day, and any guided hike or museum slot are the items that disappear in high season. A diver who waits until the wind arrives is competing with everyone else who waited.

Leave the last day unbooked. A spare day at the end absorbs a cancelled boat, a delayed flight or a missed connection without touching the rest of the plan.

What does a landlocked town near the water offer a diver?

A landlocked base gives a diver three things a coastal strip often does not: a dry place to sleep, a reason to stop diving for a day, and a change of air.

Altitude is the trade. A town at 2,000 metres sits well above the 300 metre and 2,400 metre thresholds in the post-dive guidance, so the timing matters. Put the inland day at the end of the trip, after the last dive, or at the start before the first one.

Dry air is the benefit. A diver with a week of salt and damp clothing behind them will sleep better in dry air, and gear dries overnight in a way it does not at the coast.

Walking is the activity. A landlocked town with a trail network, a museum quarter or a historic centre gives the legs something to do that is not a fin kick, and the surface interval becomes a real rest rather than a wait.

How does a diver keep skills ticking over on land?

Skills decay fastest in the first weeks after certification and slow down afterwards, but a long gap still shows. A land day is enough to slow the loss.

Rehearse the dry drills. Regulator recovery, mask clearing and buoyancy breathing patterns can all be practised on land with a mask and a cylinder valve, or with no kit at all for the breathing pattern.

Read the tables or the computer. A diver who has not looked at a dive plan since the last trip will be slow on the first boat. Twenty minutes with the planning tool on the spare day removes that.

Check the kit. Regulator hoses, O-rings, mask strap and computer battery are the four items that fail on a trip. A land day is the time to find out, not the morning of a boat.

What the entry does not settle

The altitude figures above are planning figures, not a medical clearance. A diver with a history of decompression illness, a patent foramen ovale or a recent dive injury should take advice from a diving physician before adding altitude to a trip. The entry also does not settle how many spare days a given destination needs, because that depends on the season and the local wind pattern. A diver can check the historical wind record for the destination before booking, and treat the spare day as part of the dive plan rather than a gap in it.