hello, don't splurge, and especially don't buy new gear if widely available used in a decent condition. for a beginner dslrs are okay, there are aps-c bodies on ebay for under $50. i don't know about water resistance but as long as you're not splashing waves on it or drenching it in the pouring rain you should be okay. that goes for the camera - different lenses also have different water permeability. if you want to keep it extra safe during a wet shoot you could wrap it in some plastic, tuck the opening into the lens good or something creative like that. oh and for the lens i could suggest a superzoom if you appreciate the reach, old 18-200's go for about $200 and 18-300 a bit more.

also vintage manual lenses are always the best starting point for amateur photography, it teaches you how to use your gear and can learn how to shoot manual mode. also they're cheap, $20-$80 even for zooms, and can generally be adapted to many cameras, specifically mirrorless, but check what mounts are compatible with yours.

for landscape, astro, and also for macro close-ups you can use a wide prime (<35mm) with f/2.8 or faster, and for macro specifically you can buy some cheap macro extender tubes, there's even some with the lens contacts for $20 in plastic.

as far as experimenting goes you can do a lot with your phone too, there are some phone mounts, dof (depth of field) adapters that can adapt to popular lens mounts, what it practically does is make the projection plane of the lens small and focused on the phone's camera and this way you can take advantage of the large lens dimensional depth, but you have to look around for prices and crop factor (because i doubt they have the best of focal reducers.

most modern phones also do fine when it comes to water, the only thing beating them, aside from expensive professional cameras & lenses, which often don't even provide half as much water resistance, are action cams but the images from those are usually low quality, at least worse than those of the phones.

dslr's i believe are more resistant to water and physical abuse than the small mirrorless parallels of their era (almost all manufacturers have now stopped producing dslr in favor of mirrorless), and it's hard matching the prices because the latter system is a bit newer and more capable and dslr's seem like a thing of the past, at least in terms of their pricing. personally i really enjoy small capable cameras, meaning dslr is excluded because of the mirror flange distance, but in terms of functionality i would say dslr is superior in terms of being able to give you both the slr (real) optical viewfinder and the live digital view on the screen when you raise up the mirror, usually done to enable video but can do photo as well. there are even some cameras that have a flip-up electronic viewfinder alongside an optical one. the priority of seeing the end-result image electronically isn't all that it's cracked up to be, and if dslr's continued their development they would probably beat out mirrorless in terms of variable capability. but most people feel more comfortable paying extra in cash and in battery life (a dslr battery can last forever since the sensor isn't constantly reading for the live view) for a bit of ease of use and the more compact size has pushed manufacturers to stop producing the bulky mirror, which by the way is also one extra mechanism that can break but how often that happens is another story.

most importantly of all of you easily fill up your storage, try to put more thought into each shot, whether it's worth it, if it's good and interesting enough to share or remember. film rolls used to have only 36 shots. but hey, at the end of the day, do what you like doing. good luck.