This is a short story I just wrote as practice about one of my childhood experiences.  I have done a loose translation of the feeling I was trying to capture with the essay rather than direct word for word. Some of the sentences I have intentionally made more casual to express the emotion rather than maintain the desu/masu endings in every sentence. Kanji typed is kanji I used in my handwritten version.
*A few vocabulary notes at the end with a few uncommon words and things that had been changed when someone looked over it for me.

子供のころ、夏のある日、家族と　バフロー・リバーと言う川に行きました。　　いつも川に行った時は、火を点けたり、料理したり、およいだりしました。　この時は　ジャック・クストーが大好きで、スキュバダイバーに　なりたかった。　シュノーケルとマスクを　持って行きました。

One summer when I was a kid, I went with my family to the Buffalo River. Anytime we went, we always made a fire, cooked, and swam in the river. At this time, I was really interested in Jacques Cousteau and wanted to become a scuba diver and had brought my mask and snorkel with me.

大きい岩のところでおよぎました。　川はふかくなかった。　この岩はつつみと川の中にありました。いちぶの岩の下でおよげました。　ぼくは　ワクワクしました。小さいほらあなみたいだった。　すぐ、たくさんのきいろいしまのかめを見られました。

I ended up swimming around a very large rock in a part of the river that wasn’t too deep. Part of this rock sat on the riverbank and part extended into the river. I discovered an area under the rock that I could swim under that felt like a small cave. Soon after that I found that there were turtles with yellow stripes under there.

ぼくは川からいそいで出ました。「お父さん！　お父さん！　かめをみた！」と　言いました。
父が「行ってとれば？」と　言いました。
父に「どうやって？」と聞きました。
ちちが「あしでとる」と　こたえました。

I hurried out of the river to tell my father, “Dad! Dad! I found turtles under the rock!”
My dad just responded, “Well, why didn’t you catch one?”
I asked him, “How do I catch one?”
He simply told me to grab one by the leg.

ぼくは川に入って岩ノ下でおよぎました。　かめは　十二ひきぐらい　いました。　半分のかめの頭は　水の上にありました。　ぼくは　近くに行った。　水の下に頭があるかめが　ずいぶん　いそいで　岩の下から出ました。　ぼくは　かめの足をつかみました。

I turned around and went back into the river and back under the large rock. There were maybe 12 turtles under there. Half had their heads above water. As I got close to them, those with their heads below water shot off with surprising speed. The other turtles didn’t see me and I reached forward, catching one by the leg.

岩の下に出て　かめを引きました。　かめは　ていこうしました。　ぼくのうでは　かめに　つめで　きずつけられました。　つぎに　ぼくは　かめのこうらを　つかんで　頭の上に　あげました。
「とった！　見て、とった！」と言いました。

I backed out from under the rock, pulling the struggling turtle with me. I managed to get a scratch on my arm from the turtle’s clawing. I then grabbed the turtle by the shell, holding it over my head. “I caught it! Look, I caught it!” I announced.

水の上で　かめは　重くて大きかった。　つつみに　いそいで行きました。　父と母がかめを　見た後で、かめを　にがしました。　ぼくは　とっても　うれしかった。

Above the water, the turtle was much bigger than it looked under the rock and rather heavy. I took it to the bank of the river where my parents were. After they had a chance to see the turtle, I let it go back into the river quite pleased with myself.

とる – to catch
岩 – いわ This is a large rock, generally bigger than what a person can lift as opposed to 石　いし which is a stone.
いちぶ – a section / part
つつみ – riverbank
ほらあな – cave
みたいだった – casual way to say “looked like” past tense of みたい
ワクワクする – to be excited about something
いそいで – quickly / fast, used the same way as 早い – はやい but when referring to yourself or the subject rather than something you are witnessing.
つかむ – to grab
かめのこうら – Turtle’s shell
にがす – release (allow to run away)