[1] He joined the Portuguese Navy in 1870 at the age of 20 and attended Escola Prática de Artilharia Naval in 1871.

In April 1875, he sailed on the Duque de Terceira for Portuguese São Tomé and Príncipe and various ports of South America.

His ancestor, Thomas Hickling, had been an ardent American revolutionary, and had in fact left Boston for the Azores following an argument with his loyalist father.

[2] Ivens went on an expedition into the provinces of Angola and Mozambique beginning on 11 May 1877, and studied relations between hydrographic basins in Zambezi.

Ivens, as requested by the King Luís I, and in the aftermath of the Berlin Conference, to travel between Angola and Mozambique, which ended in over 4,500 miles (about 8,300 km) of which 1/3 was uncharted in what was called "Pink Map".