[4] The two hydrographic survey vessels of the Snellius class were built at different shipyards in the Netherlands.

[6] They had echo sounders that could reach a depth of nine kilometres (5.6 mi) and a sonar that could record unevenness on the sea floor as long as the sea floor was within a distance of one kilometre (0.62 mi) below the ship.

[8] Between 1952 and 1962 the vessels of the Snellius class mostly performed surveys in Dutch New Guinea.

[10] Between 1965 and 1969 the survey vessels were active in Suriname and mapped the whole Surinamese continental plate and all the estuaries.

[11] Between 1970 and 1973 Snellius and Luymes alternately participated in an international oceanographic survey that was conducted in the Caribbean Sea, the Gulf of Mexico and the waters between the northern part of South America and the estuary of the Amazon River.