If it is on the surface or within a foot or two then a glass jar would work with a rubber seal
If your talking 20-30 feet then I would suggest keeping most of the electronics on the surface and use one wire temp probe (Water proof), a small SPI or I2C camera module again on a long wire and a pressure module designed for the depths (A pressure measurement of the water is what I assume you want, not the pressure inside any container it may be in.
What is your skill level for building a waterproof container out of Plexiglas or acrylic
The temp probe in contact with the container will give reasonable readings, the camera would simple shoot through the clear container / window, the pressure sensor would still require access to the outside pressure, either by using a flexible panel (Rubber seal, or something) to equalize the pressure inside the container or by having it mounted and sealed through a hole in the container
goes down to 100 feet, everything can go inside, if you secure the temp probe to the inside of the case it will give a close reading of the outside temp
Pressure sensor is still the issue where you will need to probably drill a hole through the case and then very carefully seal the pressure sensor through the hole. Again, need a sensor designed for submersion, not altitude
this case will allow you to put everything inside, the camera should still be able to see through the case. The Parylene will help to protect the circuit boards and the likes but your camera probably wont like it and neither would the pressure sensor
