This piece uses rolling, wave-like arpeggiated figures to evoke a sense of fluid motion. It is distinguished by its lush, late-Romantic harmonic language.
At Henle 4 this is an intermediate piece that expects secure technique and real attention to phrasing. The main demands: sweeping arpeggio figures that must stay smooth across positions; a true singing tone, with the melody floating above the accompaniment; and a left hand with real melodic or rhythmic responsibility of its own.
The main technical hurdle is maintaining fluid, consistent motion in the arpeggios while keeping the melodic line distinct.
Comparable difficulty and character — good candidates for what to learn next.
A level or two down with the same spirit — ideal if this piece is still out of reach.
Where this piece's skills lead: slightly harder works making similar technical demands.
Devaneio sobre as ondas (Op.87) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 6.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Devaneio sobre as ondas (Op.87) lasts about 5 minutes.
Devaneio sobre as ondas (Op.87) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Borboleta by Glauco Velásquez, Gymnopédie No. 1 by Erik Satie, Berceuse héroïque by Claude Debussy — see the full similar-pieces list on this page.