For those of us here, the magic of nearby Thai beaches can fade. During the day the seashore is filled with selfie-snapping goons and Septuagenarian Europeans in speedos, and don’t forget the inescapable lullaby of nightly godawful techno. 
The expense, the transport, the apocalyptic piles of plastic washed in with every tide—there is a better way. While Khao Yai is hardly a secret from the tourist hordes, outside the national park are Thai-run hotels on lazy rivers like Muak Lek with enough space to never have to see a selfie stick. 
The larger hotels can have rivers—they can even be quiet—but for anyone wanting a chill time to commune with nature in a tube drinking vodka sodas from a thermos, these just won’t do. Sorry, Intercontinental Khao Yai, you’re amazing, but this isn’t about you.
A cheap example (and a favorite) is the Baan Mailueang Hotel in Muak Lek about nine kilometers north of the highway—simple, basic bungalows. Their river on one side is a thick greenery, and on the other filled with camping families in tents and barbecuing, all with running water and a stream split by greenery. Take a folding chair, a cooler, and sit in the clear river water eating pad kaprao until you go pruney. There are a dozen similar spots just like these on the Muak Lek stream—Rai Thanthip Resort, Rai Kusuma Resort, Ban Ing Nam Resort—take your pick of rooms less than B1,000 a night.
Just south of that is the Ndol Streamside Thai Villas that’s perhaps a little more hotel-goer friendly—think big, modern rooms and a small stream play area for getting your feet wet. If you want to go the other direction, tent up and head for Jeab Camp Muaklek, which is a campground with fun on both sides of the river. 
Photo: Watermill Resort / Watermill Resort 
Muak Lek is perhaps the most well-known of the easy rivers north of Khao Yai, splitting into several streams the closer you get to the national park. But when it comes to river life in Khao Yai, you have plenty of options. Another favorite is the Watermill Resort right off the main highway about 25 kilometers from Muak Lek, which combines the best of both worlds on the Lam Takhong, a marriage of a large water area for tubing and chilling (as well as boating and kayaking) with running water . They’ve also got something that’s rare for this price point: a breakfast buffet with freshly made bread and home made bagels.  
The wildlife, plush hotels, cowboy festivals—there are a lot of reasons to go to Khao Yai. But, if you’re going with a group and your goal is drink, laugh, and stare at bugs, then you need to fill up a cooler and get yourself to Bangkok’s favorite backyard playground. 
Thus, in the words of the Notorious BIG, “f*ck beaches, get muddy”—or something like that.

Advice for river life

Muddy bottoms: Ew, you might think, hours in mud? Wrong. These are usually man made eddies in the water from mined sand; terrible for the environment, but good for you. You’ll spend time with your toes in the sand just like you would at the beach. Leave your flip-flops on the shore.
Go in a group: Sure, you can try a romantic weekend in a Khao Yai river, but you should find four or five people you don’t mind chatting in the river with for most of the day—and someone might have to make a beer run. 
Know your hotel: You can’t just pop to the 7-Eleven out here. Make sure your hotel has food and adult beverages of your choice and plan ahead. You can’t drink and drive, so bring a cooler full of food or booze as needed. 
Folding chair: This isn’t a must, but it can be helpful. Take a few folding chairs you don’t mind getting dirty in the river for when you get tired of trying to float—preferably one with cupholders. Freshwater may be calmer, but it’s less buoyant.
Be nice: Try and keep your group to a dull roar. Some people are here for a romantic weekend, so don’t ruin it. Also, treat the kayaks, tubes, and boats with respect. Muak Lek prides itself on its cowboys, and you don’t want to find yourself in a High Noon situation—or worse, Deliverance
Watch the seasons: Rivers can get a little wild in the wet season, so remember to keep the calendar in mind. Up river spots can get a little rough, and you might miss some running water sounds if it's deep in the dry season.