An obstacle may seem insurmountable.
"Insurmountable" means that something can't be overcome, as in an "insurmountable obstacle".
Something which is "insurmountable" is something which can not be overcome - as in:- Insurmountable technical problems brought an end to the project.
It is better to use "insurmountable." "Insurmountable" is the correct spelling and means something that cannot be overcome.
something apparently impossible to do
"Insurmountable" refers to something that cannot be overcome or surpassed. It often describes obstacles or challenges that are extremely difficult or impossible to conquer.
They are insurmountable and unsurmountable
The mountain we tried to climb was insurmountable.
An insurmountable problem is a challenge or obstacle that seems impossible to overcome or resolve, often due to its complexity, scale, or the limitations of available resources. Such problems can arise in various contexts, including personal, social, or systemic issues. While they may appear daunting, innovative thinking and collaboration can sometimes lead to unexpected solutions. However, the term emphasizes the difficulty and perceived hopelessness of the situation.
impossible
Despite insurmountable obstacles in his life, he had done very well.
impossible
Manageable.