To go on a countryside trip in English is to "go on a hike" or "go for a hike". This phrase comes from the idea of walking on a trail or path through the countryside.

Here are some examples of this phrase in use:

"I love going on hikes on the weekends to get some fresh air and exercise." (我喜欢在周末去郊游，呼吸新鲜空气，锻炼身体。)

"Do you want to come with us on our hike tomorrow? We're planning to go to the mountains." (你想和我们一起明天去郊游吗？我们打算去山上。)

"I used to go on hikes all the time when I was younger, but now I don't have as much time." (我年轻时常常去郊游，但现在我没那么多时间了。)

Another way to say "go on a countryside trip" in English is to "go on a nature walk" or "go for a nature walk". This phrase emphasizes the focus on observing and appreciating nature while on the trip.

Here are some examples of this phrase in use:

"We're going on a nature walk this weekend. Do you want to join us?" (我们这个周末要去郊游，你想和我们一起吗？)

"I find nature walks to be very relaxing and meditative. They help me clear my mind and recharge." (我发现郊游非常放松和冥想，帮助我清除思绪，恢复精力。)

"My favorite part of nature walks is being able to see all the different plants and animals in their natural habitats." (我最喜欢郊游的一部分是能看到所有不同的植物和动物在它们的自然环境中。)