The modern Tridente-class submarine, a unique fuel cell AIP variant of the German Type 209PN/Type 214PN, has been in operation since 2010 with the Portuguese Navy. While three were envisioned, just two were completed– NRP Tridente (S160) and NRP Arpão (S161).
The country has made good use of these in recent deployments and in bird-dogging passing Russian warships. Speaking to the former, Arpão in August wrapped up a 120-day patrol as part of the Open Sea Initiative 23.2, in the South Atlantic, which contributed to strengthening military and diplomatic relations between Portugal and each of the countries visited — Cape Verde, Brazil, South Africa, Angola, and Morocco– having traveled more than 13,000 miles and spent over 2,500 hours underway.
She reportedly covered the length of the African continent submerged in 15 days.

Arpão (FrigCapt. Taveira Pinto) arrived in Lisbon in August after her deployment which made her the first Portuguese submarine to carry out an equator-crossing mission.
Turning around just 60 days later, Arpão has deployed again, this time to the Med as part of NATO’s Operation Sea Guardian, on a patrol that will run into December and include taking part in Dynamic Mariner 23.
She is a good-looking boat for sure.
Portuguese Sub Heritage
As noted in this week’s Warship Wednesday, in 1914 Portugal had a single submarine to its name, a small Fiat-designed La Spezia-built boat, dubbed Espadarte (Swordfish). Ordered in 1910, this 148-foot/300-ton diesel-electric boat would remain in service until 1930.
She was very active, if nothing else providing an OPFOR for the fleet.
To replace their well-worn little Italian boat and expand their force, Portugal ordered a pair of modified Squalo class boats from C.R.D.A in Trieste in 1931. However, Mussolini ordered them seized on the ways in 1935 and pressed into service as the Glauco class off Spain, where the Italian “pirate submarine” fleet was very active.
This left Lisbon without any subs for a generation until they managed to pick up a trio of WWII surplus British 217-foot/990-ton S-class boats in 1948: HMS Spur/NRP Narval (S160), HMS Saga/NRP Náutilo (S161), and HMS Spearhead/NRP Neptuno (S162).
These remained in service into the late 1960s.
Then, in 1967, Portugal ordered a four-pack of French Daphné type SSKs that entered service as the Albacora-class by the end of the decade.
While one– NRP Cachalote (S165)— was sold to Pakistan after the Carnation Revolution and the military fell out of favor, the other three (Albacora S163, Barracuda S164, and Delfim S166) would be retained into the 2000s, replaced by the current German boats.