In search of some battery help

I am a newbie. I am making a custom board. I have a Maytech MT170182 motor, 300A ESC. I need to source a small (< or equal to 8"x 11" x 4" battery) waterproof battery that will be compatible. Any advice? Thank you in advance!!!

Best option would be to make it yourself with 18650 cells. They are way safer than any lipos, and you will get much more runtime from them.

Thank you for the reply. I actually had a lithium battery explode on me and caused significant damage in my office. What if these batteries get wet? Can they be placed in an airtight non-water cooled enclosure? Could I hire you to help me design/build a suitable size battery that will be provide adequate power vs time? Thank you so much.

I will send you email shortly.
Best regards