Sayyiduna Abdullah bin Umar (may Allah be pleased with him) said: Asim bin Umar and Abd al-Rahman bin Zayd both plunged into the sea and were diving, each pushing the other's head under water, while Sayyiduna Umar (may Allah be pleased with him) was watching them, and he did not object to it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9135