Ernesto Valverde has won league titles in Spain and Greece and the Copa del Rey with Barcelona as both player and coach, but the Athletic Bilbao manager said Saturday's Spanish cup final triumph over Mallorca was "incomparable".

Athletic edged underdogs Mallorca 4-2 on penalties after a tense 1-1 draw left two sides that could not be separated following 120 minutes of high-intensity football.

It was the Basque club's 24th Copa trophy -- only Barcelona have more -- but their first major silverware for 40 agonising years.

During that time they have reached the final six times but lost on every occasion until Saturday at a packed La Cartuja stadium in Seville.

Fans travelled in droves from the north of Spain to the sunny south to watch their team lift the club's first major trophy since 1984.

None of the current squad were born then but, with the club's unique stance of only using Basque origin players, the vast majority grew up dreaming of emulating that success.

The domestic double winning team boarded an iconic boat known as the 'Gabarra' to celebrate, and the current squad will follow suit next week.

"It's incredible, it's incomparable to any other (triumph)," a delighted Valverde told reporters in the early hours of Sunday morning.

"You just have to see how the stadium was, the fans who came."

Valverde, under-appreciated at Barcelona where he won two league titles in his first two seasons and was sacked with the team top of the table during his third, has forged a dynamic, exciting side after being appointed in 2022.

Athletic, propelled on the flanks by brothers Inaki and Nico Williams, play "rock 'n' roll", football according to midfielder Ander Herrera, the former Manchester United player.

The club's feted Lezama academy has produced plenty of impressive players over the past decades but the current squad boasts some of the finest young talent yet.

Goalkeeper Julen Agirrezabala, who crucially saved Manu Morlanes' penalty in the shoot-out, is 23 -- and currently is only the back-up to Unai Simon.

Oihan Sancet, who scored the equaliser in the final, is the same age and has started to stake his claim for a role in the Spain squad, while the man of the match in the final, Nico Williams, 21, has blistering pace and exquisite skill.

Dani Vivian, a recent Spain debutant, is 24, and midfielders Unai Garcia and Benat Prados are 20 and 23 respectively, with their best years lying ahead of them.

Athletic hope cup success will not be the end of the ride. Fifth in La Liga, Los Leones are battling to qualify for next season's Champions League.

They have only managed that once in the 21st century, finishing fourth in the 2013-14 season.

Aymeric Laporte, Aritz Aduriz and Iker Muniain were the key figures that season but the current crop has a higher ceiling -- currently the clouds, according to Valverde.

Muniain, 31, is no longer a regular starter but after suffering four final defeats, was finally able to get his hands on the trophy.

"Sometimes dreams come true," the playmaker wrote on Instagram, under a photo of himself lying in bed with the giant cup.

What is next? "For now just a good celebration, which is usually something big," joked Valverde.

"Later, someone will have to get them down from the clouds and focus on La Liga, and that someone is usually the coach."