Can I just wear athletic shorts and a tank top?

You can, but you will be vulnerable to mosquito-borne illnesses and sharp brush. It is better to wear breathable long sleeves that keep the bugs off so you can focus on your camera settings rather than swatting insects.

Why not wear waterproof rain gear?

Waterproof jackets create a 'boil-in-the-bag' effect. In the rainforest, you will get wet from humidity and sweat anyway; your goal is to wear clothes that dry out within 30 minutes of the rain stopping.

Staying Cool While Shooting in the Rainforest

Prioritize high-performance synthetic fabrics that wick moisture instantly and choose loose-fitting, light-colored long sleeves to protect against insects. Avoid cotton entirely, as it stays wet and heavy, causing you to overheat and creating a breeding ground for bacteria.

Select the right fabric. Look for labels that specify 'moisture-wicking' or 'quick-dry' synthetic blends (nylon or polyester). Avoid heavy base layers. If you must wear a base, look for ultralight merino wool, which manages heat better than cotton but dries faster.
Opt for 'Sun Hoodies'. Wear a lightweight, hooded UPF-rated long sleeve shirt. The hood protects your neck from the sun and biting insects without requiring a bulky hat that traps heat against your head.
Prioritize ventilation over coverage. Choose pants with laser-cut ventilation or mesh panels at the knees and thighs. Ensure your shirt has pit vents or a back ventilation flap, which allows airflow while you are carrying a heavy camera harness.
Choose the right footwear for dampness. Wear quick-dry trail runners paired with merino wool hiking socks. Avoid waterproof Gore-Tex boots unless you are in extreme mud; they trap sweat and heat inside, making your feet feel like they are in a sauna.

Can I just wear athletic shorts and a tank top?: You can, but you will be vulnerable to mosquito-borne illnesses and sharp brush. It is better to wear breathable long sleeves that keep the bugs off so you can focus on your camera settings rather than swatting insects.
Why not wear waterproof rain gear?: Waterproof jackets create a 'boil-in-the-bag' effect. In the rainforest, you will get wet from humidity and sweat anyway; your goal is to wear clothes that dry out within 30 minutes of the rain stopping.