These are recommendations, Where the temperature is mild, above 15, and most of the days are sunny. So it is not far from mind to could experience most of the days sunny, beside the beach or your hotel swimming pool, and enjoying Mediterranean Climate in the winter months from December to March.
Most of the hotels In these cities like Marbella and Tenerife have water-fun amusement facilities like slides, jumps, or… But you could not use them during the winter, although there are some hotels that offer you indoor swimming pools and it is possible to use their facilities even in the winter.