During the course of the John Murray Expedition some 22,000 miles of the floor of the Arabian Sea and the neighbouring areas of the Indian Ocean were mapped by means of the Echosounding apparatus. The region between India and Africa was crossed four times, namely:
(i) from Aden to Karachi,
(ii) from Bombay to Mombasa,
(iii) from Zanzibar to Colombo, and
(iv) from Colombo to Aden,
while more detailed surveys were carried out in the Gulf of Aden, the Gulf of Oman, and the region off Zanzibar.