Earliest in the year one could deep water solo in Majorca?
Well it is safe to say that the month of March is somewhat too cold.
People in Mallorca go swimming in October. But then the water temperature has been rising all summer long and it is warmer than March, which has been getting colder all winter long.
Sea swimming in October.
It should stil be warm enough and the sea should be warmer than March as it's been heating up all summer.
Using the National Center for Cold Water Safety as a guide, I would venture to say that June is the earliest you would find people swimming around Mallorca.
When they hear or think about 50F (10C) water, it doesn't sound particularly cold - or dangerous - because they're mentally comparing it to 50F (10C) air. It's a big mistake that gets a lot of people killed each year.
You should treat any water temperature below 70F with caution.
Water Temperature Safety Guide:
Below 77F (25C)
Breathing begins to be affected.
This is why the official water temperature required for Olympic swimming competition is 77-82F (25-28C).
70-60F (21-15C) Dangerous:
Controlling your breathing and holding your breath becomes progressively more difficult as water temperature falls as water temperature falls from 70°F to 60°F (21°C to 15°C).
True or False: You don't need thermal protection when the water temperature is above 60F (15C).
False. You should certainly be wearing a wetsuit or drysuit below 60F, however, 60F (15C) is not the temperature at which most people should start wearing thermal protection.
60-50F (15-10C) Very Dangerous/Immediately Life-threatening:
Total loss of breathing control. Maximum intensity cold shock. Unable to control gasping and hyperventilation.
Fact: Cold shock is as extreme between 50-60F (10-15C) as it is at 35F (2C).
Most people who are unaccustomed to cold water will experience a maximum cold shock response somewhere between 50-60F (10-15C). For some individuals, this happens at 57F (14C), for others, the peak occurs at 52F (11C) and so on.
This means that an unprotected immersion in this temperature range will cause most people to completely lose control of their breathing – they will be gasping and hyperventilating as hard and fast as they can.
Since cold shock reaches its maximum intensity between 50-60F (10-15C), it can’t get any more intense at lower water temperatures. In other words, breathing control, once completely lost, cannot be lost to a greater degree.
Below 40F (5C) Very Dangerous/Immediately Life-threatening:
Total loss of breathing control. Unable to control gasping and hyperventilation. Water feels painfully cold.
Below 40F (4.5C), water is so painfully cold that it often feels like it’s burning your skin. For many people, the notorious “ice cream headache” can be triggered simply by water touching your face. Even though cold shock is no more intense than it was between 50-60F (10-15C), the severe pain makes a desperate situation even worse because it greatly increases your psychological stress. Clear thinking becomes almost impossible.
98.6F(37C) Normal body temperature measured with an oral thermometer.
99.6F(37.5C) Deep body or core temperature measured with a rectal thermometer.
95F(35C) For medical purposes, this is the clinical point at which hypothermia begins.
91F(32.7C) The temperature of your skin.
85F(29.4C) Water feels pleasantly cool rather than warm.
77-82F(25-28C) Swimming pool temperature range for Olympic competition.
70F(21C) Water feels quite cold to most people. Treat any water temperature below 70F (21C) with caution.
40F(4.4C) or lower Water is painfully cold.
The National Center for Cold Water Safety
Now let us take this information and compare it to the water temperatures of the Mediterranean Sea and see what it reveals.
Mediterranean Sea is a geographical landform. The water temperature around Mediterranean Sea varies extremely year round. The temperature ranges from 15.4°C (59.7°F) in March up to 26.3°C (79.4°F) in the month of August, as shown in the interactive table below. The average water temperature throughout the year is 20°C (68°F) and the best time for water activities is late summer, since Mediterranean Sea is located in the northern hemisphere. - Sea temperatures, water sports and vacation activities near Mediterranean Sea
Taken from the above link, the average water temperature in May is 18°C and about 24°C in June. Since the temperature in May is well below 21°C, it would be same to assume that people could be swimming around Mallorca sometime in early June, but not earlier.
Keep an eye on water temperatures as temperatures may vary year to year. The Water Temperature site also gives you the present water temperature of the Mediterranean Sea in real time.