Strait of Gibraltar is blessed with wonderful habitants—whales, dolphins, and other marine mammals roam the waters south of Spain all year round. However, whale watching cruises usually operate from February or March to October or November. So the best time to hop on a whale-watching cruise is from March to October. Tours depart from the small town of Tarifa set on the very southern tip of the country—in the province of Cádiz, Andalusia. Tarifa is also the southernmost town found on the European mainland. It's about a two-hour drive from Seville.
The probability of sighting in the area is 99%, but you never know which species you'll encounter as all these animals are in the wild. Dolphins and Pilot Whales stay in the area throughout the year, while other species are seasonal. Orcas follow the tuna which migrate to the Mediterranean sea between June and August, so summer is the best time to catch a glimpse of the killer whales. Note that summer months are also the busiest time here. Sperm whales visit the Strait of Gibraltar between April and August. Fin whales are somewhat unpredictable and may occasionally be observed crossing the Strait.
Most whale watching trips last for two hours. Only if there's a good probability of the orca sighting, the time in the sea is extended to three hours. To increase your chances, it's recommended to go on a tour twice in a day. Also, remember to book your tour several days in advance and confirm a day before the trip.
Usually, the boats set off a few times per day, but be prepared for tour cancellations in case of unfavourable weather. Tarifa enjoys another fancy title—the capital of wind, and there were times when tours didn't run for over ten days in a row. The tours don't run on foggy days either.