Ar un bore hyfryd yn Ne Cymru, yng nghanol coedwig hudolus Betws-y-Coed, roedd tri ffrind yn penderfynu mynd am dro ar y mynydd.

On a lovely morning in North Wales, in the midst of the enchanting forest of Betws-y-Coed, three friends decided to go for a walk in the mountains.

Dylan oedd y mwyaf anturus, Rhys yn dwlu ar natur, a Megan yn ffotograffydd brwd.

Dylan was the most adventurous, Rhys loved nature, and Megan was an enthusiastic photographer.

Roedden nhw'n llawn cyffro am y diwrnod o'u blaenau ond doedd dim un ohonyn nhw wedi disgwyl yr hyn fyddai'n digwydd.

They were all full of excitement for the day ahead, but none of them had expected what would happen.

Wrth iddyn nhw ddechrau eu taith ar y llwybr mynydd, gwelsant ddefaid yn pori ymhlith y grug.

As they began their journey on the mountain path, they saw sheep grazing among the heather.

Roedd un ddafad yn wahanol i'r lleill - roedd ganddi golwg ddeallus yn ei llygaid, fel pe bai hi'n gwybod rhagor na dafad arferol.

One sheep was different from the others - she had an intelligent look in her eyes, as if she knew more than an ordinary sheep.

Rhoddodd Dylan enw arni yn syth: "Gwnawn ni ei galw hi'n Seren," meddai'n chwareus.

Dylan immediately gave her a name: "We'll call her Seren," he said playfully.

Nid oedd hi'n hir cyn iddynt sylwi bod Seren yn eu dilyn.

It wasn't long before they noticed that Seren was following them.

Roedd hi'n mynd â nhw tuag at y copa, bob tro y byddan nhw'n troi mewn cyfeiriad anghywir, byddai Seren yn blewynio a'u harwain yn ôl i'r llwybr cywir.

She would lead them towards the summit, and every time they turned in the wrong direction, Seren would bleat and guide them back to the right path.

Rhys, ffan o bynciau chwedlonol a mytholeg, ddechreuodd awgrymu y gallai Seren fod yn warchodwraig y bryniau hyn.

Rhys, a fan of folklore and mythology, began to suggest that Seren could be the guardian of these hills.

Gyda Seren yn arwain, cyrhaeddon nhw'r copa llawer haws nag oedd disgwyl.

With Seren leading the way, they reached the summit much easier than expected.

Roedd y golygfeydd o'r top yn anhygoel; coedydd gwyrddion, afonydd yn disgleirio dan yr haul, a'r mynyddoedd y tu hwnt yn dal eu gwyliadwriaeth.

The views from the top were incredible; green forests, rivers sparkling in the sun, and the mountains beyond still keeping watch.

Aeth Megan ati i dynnu lluniau a chofnodi'r foment â'i camera.

Megan set about taking pictures and capturing the moment with her camera.

Wrth gyrraedd y gwaelod unwaith eto, aeth y criw i ddiolch i Seren am ei chymorth annisgwyl.

Upon reaching the bottom once again, the group went to thank Seren for her unexpected help.

Ond y funud roedden nhw am ei chyrraedd, roedd hi wedi diflannu yn union fel taflen yn y gwynt.

But the moment they were about to reach her, she had vanished into thin air like a sheet in the wind.

Dylan sylweddolodd fod y ddafad ddirgel hon wedi dod yn arweinydd annhebygol i grŵp o dwristiaid ar eu taith.

Dylan realized that this mysterious sheep had become an unlikely leader for a group of tourists on their journey.

Penderfynodd y tri ffrind rannu'r stori am eu harweinydd ffodus â phobl y pentref ac fe daenodd y chwedl o amgylch Betws-y-Coed.

The three friends decided to share the story of their fortunate leader with the people of the village, and thus, the legend of Betws-y-Coed spread.

O hynny ymlaen, roedd pobl bob amser yn edrych am y ddafad ddirgel, gan obeithio y gallai hi, hefyd, efallai y byddai'n cynnig arweiniad i eraill ar eu taith trwy' r mynyddoedd hudolus hyn.

From then on, people were always on the lookout for the mysterious sheep, hoping that she, too, might offer guidance to others on their journey through these enchanting mountains.

Ac fel hyn, aeth y dydd yn nos, a Seren, y ddafad arwrol, yn rhan o hanes a allwn ni byth anghofio.

And so, the day turned into night, with Seren, the brave sheep, becoming part of a tale that we could never forget.