Un diwrnod braf, ym mherfeddion Caerphilly, a'i gastell anferth fel cefndir, roedd Rhys yn barod am antur yn ucheldiroedd garw Eryri.

One fine day, in the foothills of Caerphilly, with its vast castle as a backdrop, Rhys was ready for an adventure in the rugged heights of Snowdonia.

Roedd y niwl trwchus yn gorchuddio'r bryniau fel carthen o arian, ac roedd y gwlybaniaeth yn wlyb i'r esgid.

The thick fog covered the hills like a sheet of silver, and the moisture made the ground damp.

Rhys oedd yn anturwr, plentyn y mynydd, gyda chalon yn llawn cyffro.

Rhys was an adventurer, a child of the mountains, with a heart full of excitement.

Ond Megan, ffrind gorau Rhys, roedd hi ar goll rywle yn y cymylau.

But Megan, Rhys's best friend, was lost somewhere in the clouds.

Roeddent wedi ysgaru tra roedden nhw'n cerdded, a'r niwl yn trwchusach nag erioed.

They had become separated while walking, and the fog was thicker than ever.

"Rhys?

"Rhys?"

" Llefai lais yn y pellter, ond doedd hi ddim Megan.

A voice called in the distance, but it wasn't Megan.

Ond, cafodd Rhys syniad.

But Rhys had an idea.

Petai ef yn siarad yn uchel, efallai bydd Megan yn ei chlywed.

If he spoke loudly, perhaps Megan would hear him.

Sut rhyfeddodd Rhys wrth weld cysgod siâp yr hyn oedd yn ymddangos fel merch yn sefyll yn llonydd ln cymell Rhys i sibrwd, "Megan, ti'n iawn?

Rhys was surprised to see a shadow shaped like a girl standing silently, prompting him to whisper, "Megan, are you okay?"

"Ond ymateb ddim oedd, dim ond stariad gwag a dychryn.

But there was no response, only empty silence and fear.

Siaradodd Rhys eto, ond y tro hwn gyda chadernid, "Megan, ti wedi dy gamgymryd?

Rhys spoke again, but this time with determination, "Megan, have you lost your way?

Mae'r niwl a'r tywyllwch yn cymylu popeth.

The fog and darkness are clouding everything."

"Yna, wrth i niwl plygu a thoddi'n raddol, dadorchuddiwyd y gwir.

Then, as the fog slowly bent and began to melt away, the truth was revealed.

Nid Megan oedd hi, ond dafad wen, placid, yn bwyta glaswellt gyda dim syniad o'r ddryswch.

It wasn't Megan, but a white sheep, peaceful, eating grass with no sense of the confusion.

Dechreuodd Rhys chwerthin, cyntaf yn feddal, ac yna'n uchel lle mae'r mynyddoedd eu hunain yn ymuno mewn.

Rhys began to laugh, first softly, and then loudly, where the mountains themselves join in.

"Megan," ebe fe, yn ei gywilydd ond eto wedi cyffroi, "Mi wnest i gamgymeriad.

"Megan," he said, in his embarrassment but still excited, "I made a mistake."

"Ac wrth i'r niwl pellhau a'r eiliad yn troi'n stori i adrodd, dyma Megan yn camu allan o'r niwl, ei gwên mor ddisglair â'r haul.

And as the fog cleared and the moment turned into a story to tell, there was Megan stepping out of the fog, her smile as bright as the sun.

"Rhys," meddai hi, gan chwerthin wrth iddi weld Rhys yn sefyll gyda'r dafad, "Ti di ffeindio ffrind newydd?

"Rhys," she said, laughing as she saw Rhys standing with the sheep, "Have you found a new friend?"

"Roedden nhw'n cyfarch, Rhys gyda'r fronnau coch o dan ei wallt a Megan yn dal ei bol.

They greeted each other, Rhys with red cheeks beneath his hair, and Megan holding her stomach.

Ac felly gorffenedig yr antur, gyda Rhys a Megan yn ôl yn gytûn, a'r dafad a'i drwyn gwlyb yn chwedl fyddai yn hoelio'u cyfeillgarwch am amseroedd hir iawn.

And so the adventure ended, with Rhys and Megan back together, and the sheep and its wet nose a tale that would cherish their friendship for a very long time.

A chan ddeall bod hyd yn oed mewn camgymryd, mae cyfle i chwerthin a gwneud atgofion â ffrindiau yn Eryri, lle mae'r niwl yn cuddio a dadorchuddio dirgelion natur bob dydd.

And understanding that even in a mistake, there is a chance to laugh and create memories with friends in Snowdonia, where the fog hides and reveals the secrets of nature every day.