Later, back in the water and looking at the shore, we were reminded that these tiny Atlantic islands are like mini-continents, spanning a vast range of climates over a few kilometres.
Rows of palms line the desert-like beach, while cacti climb the steep base of the mountains - there are no hotels or apartments here - until more dense vegetation expands into cool laurel forests covering the spectacular volcanic peaks.
"Does the beach ever get busy?" I asked one of the vendors as the tropical spirit persuaded me to order a caipirinha cocktail.
Oh yes, he replied. Over summer weekends and on public holidays, the number 910 bus disgorges hordes of locals and the car park is full. But on a weekday you never need to look far to find a sunny spot.
Lord Nelson lost his right arm when the British fleet failed to capture Santa Cruz in 1797. But then, struggling against the tide, he made a poorer choice of beach than we did, picking a rocky spot closer to the port, where we were headed for dinner.
Santa Cruz is not the only place to go on non-beach days. At Loro Parque, Europe's answer to SeaWorld, the brilliant dolphin and killer whale displays are entertaining without being too contrived.
A few kilometres along the coast, Icod de Los Vinos is famous for its centuries-old dragon tree and the wines that give this charming town its name. Farther inland, a cable car runs up to Mt Teide, Spain's highest peak at just under 3718m, which is often snow-capped.
But the most spectacular sunset over the island was to be seen right back where we came from, just a short drive up into the hills above Las Teresitas.
CHECKLIST
Getting there: Low-price airlines Thomson Airways, Monarch, jet2, easyJet, Ryanair and Thomas Cook fly there from London.
Top tips:
• Don't leave hotel windows open. In the Canaries thieves can (and do) climb along even the highest balconies of hotels in search of wallets and phones. Just leave the air-conditioning on at night.
• Avoid the mountain roads when it's wet and dark, particularly on the narrow, winding roads leading up to Mt Teide.
Further information: See turismodecanarias.com.