Oeschinensee has been described as the most beautiful lake in the Alps, making it an obvious hiking destination. The hike begins at the Kandersteg train station. From there, follow the yellow sign east toward Oeschinensee. Turn left at the main road, then make a quick right at the next yellow sign. The trail follows a paved road, then a gravel road, for quite a while. At just over a kilometer the trail crosses a bridge over the river. At around 2.4 kilometers the road will start making switchbacks up the hill. At 4.2 kilometers you will reach the lake Oeschinensee.
At the lake you'll pass the Berghaus am Oeschinensee. Here you can walk right down to the lake. Continue along the lake until you see a yellow sign. Follow the sign toward Oberbärgli and Hohtürli. As you approach Oberbärgli you will pass a large river with views of several very large waterfalls that are especially robust in the spring and early summer. There are a few picnic tables here to stop and enjoy the views. To the east you can see the Blüemlisalpgletscher.
When you reach Oberbärgli, turn left toward Heuberg and the cable car Bergstation. This trail leads along the steep slope past several waterfalls and impressive cliffs. The trail becomes narrow in some places with steep drops, so this trail isn't recommended for very young children. However, aside from this section the trail is not very technical. There are a few stream crossings that could be difficult in spring, but they are not dangerous if you are careful.
About 2 kilometers from Oberbärgli is Heuberg, where there are a few benches with a great overlook of the lake and surrounding mountains and waterfalls.
About 3.5 kilometers from Oberbärgli you will reach an intersection with a dirt road. Turning left leads to the lake (you will also pass a restaurant with bathrooms). If you are ready to head home, turn right toward the Bergstation. Simply follow the road to the station, where you will find public bathrooms. From the station, follow the yellow sign down the hill toward Kandersteg to finish the hike.
If you want to extend your hike, there are a few out-and-back additions you can do:
You can also make the hike shorter by taking the cable car up and doing the hike in reverse.
Note that each of these hikes (especially Fründenhütte and Blümlisalphütte) can have snow fields late into the summer months. Switzerland Mobility is a helpful resource for planning your exact route. You can also use the official Swiss online map, which has more advanced tools.