the nNext summer, my family and I will go to the beach.

We gowill stay for one week in a hotel near tohe sea.

The first day, we are going towill relax and enjoying of the sun ion the beach.

My brothers and I go twill go swimming in the sea and build sandcastles of sand.

wWe are going to join a boat excursion to see dolphins and others marine animals.

Also, we are going to practice watersports, like surfing and snorkeling.

One nightAlso, we are going to dothrow a bonfire in the beach and tell histories below the stars.

Besides, wWe are going to visit someones tourist places of the zone.tourist sites.

We are going to explore the local market, where we are going to buy gifts and provetry the typical food.

Everyone wereis very excited and count ofing down the days for the holidays to arrive.

We know that it will abe an incredible experience and let's gowe will enjoying every moments together

Seventh entry

the nNext summer, my family and I will go to the beach.

We gowill stay for one week in a hotel near tohe sea.

TOn the first day, we are going to relax and enjoying of the sun ion the beach.

My brothers and I will go to swimming in the sea and build sand castles of sand.

wWe are going to a boat excursion to see dolphins and others marine animals.

Also we are going to practicdo some water sports, like surfing and snorkeling.

"Practice" makes it sound like you do the sports regularly, but "do" doesn't convey that.

One night, we are going to do a bonfire in the beach and tell histories below the stars.

Besides that, we are going to visit someones tourist places ofin the zonearea.

We are going to explore a local market, where we are going to buy gifts and prove the typitry local food.

Everyone wereis very excited and count ofing the days foruntil the holidays to arrive.

We know that it will abe an incredible experience and let's gowe will enjoying every moments together.

the nNext summer, my family and I will go to the beach.

We gowill stay for one week in a hotel near tohe sea for one week.

TOn the first day, we are going to relax and enjoying of the sun ion the beach.

You can remove "on the beach", because you already said you'll be on the beach in the first sentence. Having it twice feels a bit awkward.

My brothers and I go twill go swimming in the sea and build sandcastles of sand.

I think you should add some transition word like "then" or "after" because you started off saying "on the first day", indicating some order of events.

DLater during the week, we are goplanning to do many more fun activities.

I think it's best to include a transition like "later" or "then" before "during the week" because you are changing what you are talking about.
The "many *more*" is for emphasizing the contrast.

wWe are going towill go on a boat excursion to see dolphins and others marine animals.

Also we are going tWe will also practice watersports, like surfing and snorkeling.

"Practice" could be wrong or right depending on whether you have done them before or not. Practice is repeating something you have already learned or done before. So if you are going to do them for the first time, you would just say "We will also do watersports".

One night, we are goplanning to do a bonfire ion the beach and tell histories below the stars.

BesidesAlso, we are going to visit someones tourist places ofattractions in the zonearea.

We are going to explore a local market, where we are going to buy gifts and provtaste the typical food.

I think I understand what you mean by "typical" here-- you want to try food that is usually eaten in that area. But it is not natural English to say "typical food" when referring to a place's representative food. Instead, an often used word is "specialties" ("taste the local food specialties").

Everyone wereis very excited and is counting down the number of days before the holidays to arrive.

We know that it will abe an incredible experience and let's gothat we will enjoying every moments together

the nNext summer, my family and I will go to the beach.

We gowill stay for one week in a hotel near tohe sea for one week.

The first day, we are going to relax and enjoying of the sun in the beach.

My brothers and I go twill go swimming in the sea and build castles of sand.

or "sandcastles"

wWe are going to do a boat excursion to see dolphins and others marine animals.

Also we are going to practice watersports, like surfing and snorkeling.

One night, we are going to do a bonfire in the beach and tell histories below the stars.

BesidesAlso, we are going to visit someones tourist places ofin the zonearea.

We are going to explore the local market, where we are going to buy gifts and provetry the typical food.

Everyone wereis very excited and, count ofing the days for the holidays to arrive.

We know that it will abe an incredible experience and l. Let's go enjoying every moments together!