Roedd y dydd yn dechrau'n fyddar yng Nghwm Taf, gyda'r haul yn gwenu dros y Copaon Bannau Brycheiniog.

The day began peacefully in Cwm Taf, with the sun smiling over the peaks of the Bannau Brycheiniog.

Bydde bron pob pŵl o ddŵr yn leth i helpu Eira a Gwyn wrth iddynt baratoi ar gyfer eu taith.

Almost every pool of water was clear to help Eira and Gwyn as they prepared for their journey.

Roedd Eira yn brofiadol, yn barod i anturio, tra roedd Gwyn, ei frawd iau, yn frwdfrydig ac yn benderfynol o ddangos ei allu.

Eira was experienced, ready for adventure, while Gwyn, her younger brother, was enthusiastic and determined to show his ability.

Roedd y gobaith o gwblhau'r llwybr yn apelio, ond roedd y gwres yn uchel ar ddiwedd y gwanwyn hwn.

The hope of completing the trail was appealing, but the heat was intense at the end of this spring.

Gan ddechrau â'r bore cynnar, roedd y ddau yn cerdded llwybrau a chorstir, camerâu yn dal y golygfeydd godidog.

Starting with the early morning, the two walked paths and moorlands, cameras capturing the magnificent views.

Roedd defaid yn crwydro, a'r gwynt yn ysgafn.

Sheep roamed, and the wind was gentle.

Ond wrth dringo’r copa, sylweddolodd Eira bod y tymheredd yn codi’n sydyn.

But as they climbed the peak, Eira realized the temperature was rising rapidly.

Roedd ofni'r peryglon wrth rhyw dir cythryblus.

She feared the dangers of such turbulent terrain.

"Gwyn," meddai, "gad i ni fynd yn arafach, mae'n oeri."

"Gwyn," she said, "let's go slower, it's getting cooler."

Doedd Gwyn ddim yn gwrando; roedd awydd iddo gadw ar fynd, i gwblhau’r her.

Gwyn wasn't listening; he wanted to keep going, to complete the challenge.

Ond wrth iddo fynd ymhellach, roedd ei gamau'n dechrau gostwng.

But as he went further, his steps began to falter.

"Rydyn ni'n agos, dwi'n siŵr," roedd yn dweud, ond roedd Eira'n sylwi ar flinedd ei gamau.

"We're close, I'm sure," he said, but Eira noticed the fatigue in his steps.

Pan gyraeddon nhw fan uchaf, roedd haul yn mynnu tueddu ei ddoniol gariad.

When they reached the top, the sun insisted on displaying its playful affection.

"Gwyn, edrychwch - rhaid i ni stopio yma," annogodd Eira.

"Gwyn, look - we have to stop here," Eira urged.

Dechreuodd Gwyn deimlo'n benysgafn; arwydd clir o drawstrok gwres.

Gwyn began to feel lightheaded; a clear sign of heatstroke.

Roedd ei swyngipio yn sobor serchus.

His initial excitement turned sobering.

Heb oedi, tynnodd Eira Gwyn dan cysgod coeden, a rhoes efain i'w ben ac ei wddf.

Without hesitation, Eira pulled Gwyn under the shade of a tree and applied a damp cloth to his head and neck.

"Ein dyframa anwenol," atgoffodd Eira, troi’r ffordd i gadw Gwyn eang.

"Our unquenchable thirst," Eira reminded, finding a way to keep Gwyn alert.

Ymkindodd y ffon symid: sobri aedal, dal cân goff.

The mobile phone stirred: rescue was nearby, and help was on the way.

Cawsant gyswllt gyda cherbyd arall o deithwyr yn cerdded a oedd yn gyfarwydd, a chymryntoli eu cynal a gynnal gwasanaeth cyntaf.

They got in touch with another group of travelers who were familiar with the area and provided first aid.

Tra roedd Gwyn i wella, gallai Eira anadlu o wcog oforderihedd.

While Gwyn was recovering, Eira could breathe a sigh of relief.

Yn y diwedd, gydag ymffordd gymorth, daeth dydd diogel i ben.

In the end, with support, a safe day concluded.

Daeth Gwyn yn fwy ymwybodol o bŵer natur ac y cawson nhw brofiad buan a defnyddiol.

Gwyn became more aware of the power of nature, and they had a brief and valuable experience.

Gydag Eira yn gwerthfawrogi amgylchiadau ansicr bywyd, roedden nhw’n llawn pwyslais na fyddent byth yn gorfod gwintio â'r amser sydd ar gael.

With Eira appreciating the uncertain circumstances of life, they emphasized never to waste the time they have.

Roedd y Bannau'n sefyll yn ddiofyn, serenni wrth iddyn nhw dcymwyth gyda diolch.

The Bannau stood steadfast, shining as they moved forward with gratitude.

Roedd hwnnw’n storïa o brofiad, lle bu natur ar ei orau - a’i wleder pwysla.

It was a story of experience, where nature was at its best—and its most challenging.