Swimming in the sea is good/great fun.

在大海里游泳很有意思。

We went swimming in the sea.

我们去海里游泳了。

I like that place because I like swimming in the sea.

我喜欢那个地方，因为我喜欢在海里游泳。

It's wonderful, you can see the whales swimming in the sea, the sea lions lying on the beach and the penguins.

太棒了，你可以看到鲸鱼在海里游泳，海狮躺在沙滩上，还有企鹅。

Jimmy is swimming in the sea!

这是“现在进行时态”的句子。

What about swimming in the sea?

在海里游泳怎么样？

Swimming in the sea makes him excited.

在大海里游泳使他很兴奋。

Graduate school is like swimming in the sea.

研究生阶段就像徜徉大海。

Can you see the happy ducks swimming in the sea?

你能看到开心地在海里游泳的鸭子们吗？

We are going to the beach and going swimming in the sea.

我们去沙滩,还在海里游泳。