He is best known as host and participant of various TV reality shows and series of geography-related documentary programs, in which he appears as bushcraft expert, adventurer and traveller.

Telmo's grandfather Cecilio Aldaz Urricelqui (1887-1944) was born to a petty bourgeoisie family; following education in the Pamplonese Escuela de Artes y Oficios[3] he worked in the La Agrícola bank.

[20] She was descendant to a few distinguished Basque families; her paternal great-grandfather owned a large mayorazgo in Biscay and served as local deputy in the 1860s;[21] another one was a longtime member of Isabelline Cortes,[22] while others were Navarrese entrepreneurs.

[30] In 2006[31] Aldaz married Isabel Ussia Hornedo,[32] daughter to well-known publisher Alfonso Ussía Muñoz-Seca and great-granddaughter to Pedro Muñoz Seca.

[34] Son to a merchant marine captain and nephew to an adventure media celebrity, already during his teenage years Telmo took part in numerous travelling projects; some were related to a friend of his father and another Navarrese maritime explorer and public personality, known in Spain as Capitán Etayo.

Formatted as a holiday outdoor exploration tour and focused on Africa, it was supposed and until today is being marketed as an exercise in survival, volunteering, ecology, education, research, culture, sports, business entrepreneurship, adventure and international cooperation.

[49] Already at the time some newspapers featured him as “explorador del siglo XXI”[50] and especially the Madrid titles kept referring to him as to organizer of adventure trips for the youth.

In 2004-2005 he served as trainee production assistant during the making of Capitán Alatriste by Agustín Díaz Yanes, the second most expensive Spanish movie ever.

[53] Having gained experience Aldaz started to produce video materials from his Rumbo al Sur editions, first floated in social media.

[55] In the early 2000s Aldaz signed a contract with the Spanish branch of DMax, the European television channel and part of the Discovery network.

It featured 10 madrileños who under Aldaz’ guidance were supposed to manage on their own in the wilderness of Sierra de Guadarrama;[56] the best of them was awarded the title of “the alfa wolf” and a financial reward.

[59] In 2017 Aldaz himself became the protagonist of an episode in the popular Radiotelevisión Española series Ochentame... otra vez; titled Sangre de aventureros, it featured modern-day Spanish travelers and adventurers.

His focus was on adventure and joy,[71] though also with an important ingredient of hard work, learning, overcoming of challenges, meeting people and protecting the environment.

[76] Aldaz later claimed that growing up a Traditionalist was a natural way of maturing for him,[77] that since childhood he participated in annual rallies at Montejurra, Montserrat or Isuskiza, and that as a boy he knew many Carlist Navarrese personalities.

On the one hand, the threads related to crossing cultural frontiers, ecology and combating prejudice might have evoked left-wing leaning; on the other, the focus on Hispanidad, stress on discipline and male virtues might have appealed to the right-wing audience.

[80] He became a regular guest of a Ring podcast, produced by Diario Ya; he featured along attendees clearly associated with political right, like Santiago Abascal or Rafael López Dieguez.

[84] In 2019 he assumed a high-profile when hosting a Carlist media event in the Madrid Gran Hotel España; it was designed as a handover between the former CTC president, María Cuervo-Arango Cienfuego-Jovellanos, and the new one, Javier Garisoain Otero.

Aldaz’ first message contained numerous religious references and declared faith in the ultimate triumph of "Santa Causa del Carlismo".