Left to our own devices, audience members at the Barbican could have suggested any number of works to fit into Hélène Grimaud’s aquatic-themed recital. In an absorbing programme note, the French pianist explained that her selection wasn’t meant to be exhaustive, hence the absence of some obvious candidates. Nevertheless, the recital programme had lost some Liszt, Debussy and Ravel (Ondine) since its initial announcement, replaced with Brahms’ Second Sonata. Puzzlement indeed, yet last night’s performance was often as astonishing as the programme was surprising.

With just a spotlight on the Steinway to break the Stygian gloom, Grimaud performed her mesmerising selection of eight “Water Reflections” in a continuous sequence, unbroken (almost) by applause. Rarely have I seen a more carefully placed first note – a pianississimo D flat to open Berio’s Wasserklavier – after Grimaud had calmly settled herself and waited for absolute silence in the hall before commencing. At the end of each work, the sustain pedal (masked by her flared trousers) was often employed. Her hands would remain in position on the keyboard as the final notes decayed, before shifting into place for the next, clearly signalling her desire to link the eight works. Grimaud, our musical naiad, often seemed to be in her own world, swept up in the music, occasionally leaning back, glancing to the heavens. At the end of Debussy’s La cathédrale engloutie, the final number, it seemed cruel to break the spell and draw her back into the real world.

What surprised most in Grimaud’s “Water Reflections” was the sheer variety of playing. This wasn’t 45 minutes of demisemiquavers quietly trickling up and down the keyboard, but an intelligently balanced selection, where the sparseness of Wasserklavier and Takemitsu’s Rain Tree Sketch II was followed by a boisterous gondola ride courtesy of a Fauré barcarolle that was anything but serene until its tender final bars. Grimaud’s approach to Albéniz’s Almería had plenty of left-hand steel, while her Janáček flowed. The trio of more obvious candidates left the greatest impression on my memory. Her Liszt glistened and glittered as I sat mesmerised by rivulets and tremolos, while Ravel’s Jeux d’eau, inspired by Liszt, bristled with exuberant life, Grimaud’s left hand bouncing over the right. Her playing of La Cathédrale engloutie verged on the epic – big, muscular playing, sonorous chimes engulfing the hall as much as the sea engulfs the legendary cathedral of Ys. I simply didn’t want it to end.

Grimaud has long been a champion of Brahms and although the link to the watery theme was tenuous at best – “the musical testament of Zeus, lord of the sky, the rain god, his weapon a thunderbolt” – the performance of his Piano Sonata no. 2 in F sharp minor was staggering in its tempestuous bravura. Here was Brahms the young lion, just 19 years old, launching himself upon the world with a work which is positively Lisztian. Indeed, the young composer had played it through for Liszt, although it had to wait until 1882 for its first public performance. Grimaud tore into the score with wild abandon in a monumental reading, digging into Brahms’ thick chords with robust vigour. Even the calm Andante had rigorous inner tension, erupting in a thunderous scherzo. Her left wrist raised higher than her right, the finale was a study in fierce agitation.

Wonderful as the Brahms was, I could happily have remained submerged in the watery repertoire all evening. Grimaud must have read my mind. Almost shyly accepting her ovation, she offered first a Debussy Étude, all rippling arpeggios, followed by a shimmering Rachmaninov Etude-tableau, before ending with more Brahms. Perhaps Johannes was intended to be a fish out of water…