After arrival at Barcelona El Prat Airport, car rental will follow for the journey. You will then set off on your journey to La Molina, when entering the route into the sat nav check that the sat nav has selected the route with fees (peajes), which is much easier and more pleasant, via Manresa - Berga - Alp - La Molina. 

From the hotel, you can drive and park right in the main car park under the cable car, Telecabina Cadí-Moixeró, where you can easily find the Bike Park bike rental and all the necessary equipment, where you have been booked. 

Today they will print your FORFAIT for the Bike Park right here, 1 adult day is €28, 1 children's day is €24, you can also buy a half day from 1pm, it is then €25 adult and €20 children. 

My experience has been 1 adult (12 - 64 years old) half day forfait + bike and gear (pads, helmet, gloves) for 90 EUR, 1 child (4 - 11 years old) half day with everything for 45 EUR 

The cable car is open in summer and outside winter until 17:00. And the last trip down the cable car is at 17:30  

From the HG Molina Hotel you can walk to the cable car "Telecabina Cadí - Moixeró", with a purchased FORFAIT you can be taken up. In good conditions, as soon as you get off the cable car, you will transfer to the next cable car, which will take you to the very top, El refugio Niu de L'Aliga, and from 2,537 metres you will have a view of the whole Cerdanya, Berguedá and Ripollés area. And then you can start the descent down on foot or again by cable car (egg) down. 

From the hotel, walk to Llac de La Molina lake, where you can rent a pedal boat (€9/person), paddle surf or kayak. 

Alternatively, a small electric bike can be hired for children aged 3-8 years old, when they can cycle around the lake. After the lake activities, walk to the tubbing area. First you need to buy a ticket at the ticket office according to the number of rides for tubbing. The price is EUR 4 for 1 ride. Or 12 EUR for 6 rides. The activity is for adults and children. 

Today, plan your day your way. Obviously, you have to be guided by what time your flight leaves, but if you have plenty of time, here are some recommendations on what you can do.
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> Enjoy a nice relaxing day at the beach. A unique contrast between the atmosphere in the mountains and the sea. Taste the local cuisine.
If you feel like it, try one of the water sports. Surf, paddle surf, kayak, kite surf....Castelldefels has a 5 km long sandy beach. Nice entrance to the water. Ideal for children. It's a place that lives for sport. Nearby is the famous Olympic Canal where you can practice wake board.
> Above the city towards  north is the vast Garraf National Park, where it is possible to realize hiking tours. I definitely do not recommend visiting the beach and the national park in the month of AUGUST, due to the extreme heat in Parc Garraf and the beach due to the hot season and the large number of people. In August, almost all Spaniards enjoy their holidays on the beach. So don't expect much quiet on the beach in August and always on Sundays. Outside of this period, it is a wonderful place where there is no headache because the beach is so long that everyone has enough space to themselves!